Are you tired of  ads getting dis-approved on Facebook ? or the high CPC costs and Quality Score of Google Adwords? Go beyond Fb and Adwords .There are lot more traffic sources out there.Discover some hidden gems for your profitable campaigns.
I have compiled and listed here,  a huge list of ad networks and traffic sources which are worth trying.I have personally tried most of them.Please free to add/suggest any traffic sources that I missed out here

http://7search.com -  2nd tier PPC/Cheap search ads
http://ad.ly/ – sponsored/celeb Tweets,Twitter Advertising
http://adblade.com  – self serve display ads, good traffic
http://adbrite.com – display/contextual ads
http://adbuyer.com – media buying ad exchange
http://adclickmedia.com – self serve banners and contextual widgets
http://adengage.com – banners/text, similar to adbrite, allow weekly buys
http://adknowledge.com – social media ads,cheap ads,High Volume (aquired cubics & bidplaceSB)
http://adsonar.com – part of advertising.com(aol) -text ads on high traffic US sites  like,cnn,cnbc,Huffington post,etc
http://www.adside.com – self serve ppc, contextual, inline text ads
http://adroll.com- retargeting
http://adsrow.com -ppc
http://addesk.advertising.com – display solutions on AOL inventory
http://advertising.com – display/banners, media buys
http://advertising.ezanga.com – cheaper search and contextual
http://advertising.microsoft.com/ad-network – microsoft banner display/media buys
http://blogads.com – ads on high traffic blogs
http://bidvertiser.com – contextual and banner ads
http://buysellads.com – self serve banners on a range of design blogs
http://casalemedia.com – self serve banners
http://chitika.com – search related contextual display ads
http://clicksor.com – contextual/banners
http://clickbooth.com/advertiser/cpc  – (Formerly Adtoll)-display/text ads
http://www.contextweb.com(Formerly: adsdaq) -contextual ads/media buying exchange
http://cpmstar.com – banners display targetted at gaming sites only
http://cpxinteractive.com – banners/display, media buys
http://elephant-traffic.com – ppv type ads on parked url’s – cheap clicks
http://facebook.com/ads – self serve ads on facebook
http://finditquick.com – cheap text ads
http://google.com/adwords – You know about this anyway !
http://www.industrybrains.com (Formerly Marchex/Adhere)-Cheap PPC Advertsing
http://kontera.com – inline contextual text ads
http://linkedin.com – Ads on Linkedin pages
http://mediatraffic.com – ppv ads
http://miva.com – cheap search ads
http://myads.com – self serve banners on myspace & a host of Fox network sites
http://platform-a.com -  aol banner ad/media buy network
http://plentyoffish.com – Social media self serve ads (CPM)
http://premiumaccess.com – premium banner ad networ
http://pubmatic.com – ad network
http://pulse360.com – ads on good high traffic inventory
http://rockyouads.com – social media display ads
http://searchfeed.com – search/contextual on parked pages. shit.
http://sponsoredtweets.com – sponsored twitter posts
http://stumbleupon.com – Social media ads
http://technoratimedia.com – banners
http://trafficvance.com – good ppv ad network
http://traffiq.com – self serve banners, media buys
http://trianads.com – failbook app ads, display
http://tribalfusion.com – media buy banner network
http://www.undertone.com – premium banners/display/media buys
http://www.userplane.com – social media advertising for media buyers
http://valueclickmedia.com – banners, display/media buys
http://www.web.blogads.com – banners/text ads on high traffic blog network
http://www.adconion.com – video/banner ads, media buys
http://www.adperium.com/directads – display banners, self serve, similar to adbrite
http://www.adready.com/ads/public – display ads/self serve banners on yahoo sites
http://www.adroll.com – self serve banners
http://www.adside.com – self serve ppc contextual inline text ads
http://www.bidplacesb.com/ – self serve banners, owned by AOL
http://www.burstmedia.com – banners/display/media buys
http://www.canoeklix.com/accueil – text ads on the canoe.ca network
http://www.collective.com – media buys, banners/display
http://www.dsnrmg.com – display, media buys, unknown quantity/quality
http://www.etology.com/ – banners/text ads, cheap
http://www.interclick.com – banners, high volume media buys
http://www.isocket.com/ – closed beta, but will be banner/display ads
http://www.leadback.com – retargeted ads at search traffic
http://www.mediawhiz.com – banners/display, media buys
http://www.reseauselect.com – banner and offline targetted at quebec
http://www.rightmedia.com/ – self serve banner exchange
http://www.specificmedia.com – banners/video display, media buys
http://www.widgetbucks.com – self serve text/widget ads
http://xtendmedia.com – banner/display media buys
http://z5x.net – display banners, media buys, large inventory
https://adcenter.microsoft.com – search and content text/contextual ads
https://marketingsolutions.yahoo.com – search/content contextual ads
 
 
Additions to original traffic source list :

http://about.digg.com/ads – sponsored ads on digg.com
http://adfunky.com/ – Display/rich media, some high traffic inventory
http://aditall.com – produce and run video ad campaigns
http://adjuggler.com – display/media buys
http://admedia.com – self serve inline contextual text ads like kontera, also display ads
http://adonnetwork.com – banners, contextual, search – self serve (pop under)
http://adoori.com – ppv popups – self serve
http://advertise.com – self serve text, search and display ads
http://affinity.com – search, parked pages, text ads – good 2nd tier inventory
http://engagebdr.com – media buys on high traffic inventory (25k pre-pay)
http://www.ero-advertising.com – Web & mobile display/banners on adult inventory
http://fetchback.com – Retarget the ones who didn’t sign up first time
http://holanetworks.net – media buys targeting hispanic demo only in USA
http://inlinks.com – inline contextual ads, like Kontera
http://intermarkets.net – display/banners – media buys
http://izea.com – self serve sponsored tweets/blog posts
http://leadimpact.com – formerly zango – pops/CPV ads
http://linkworth.com – self serve contextual/inline text ads and good SEO services
http://looksmart.com – self serve search/contextual text ads
http://marketplace.sitepoint.com/cat…ertising-space – small direct banner buys
http://revtwt.com – advertising on twitter
http://traffictaxi.net – self serve banners/display/popunders – global
http://www.accelerator-media.com – UK banners/media buys
http://www.ad2onegroup.com – media buys on premium UK, Irish & Aus. sites + Ebay
http://www.adborsa.com/ – Display ads for largely Turkish demography
http://www.adconion.com – display/media buys, good for Europe
http://www.admanage.com – Contextual, inline & display, pops, parking
http://www.adoptim.com – in-video, text and banner ads
http://www.adpepper.com – European banner display + Affiliate network
http://www.adtegrity.com – Media buys/display, high volume
http://www.adverline.com – Media buys, good quality French/Euro inventory
http://www.advertisespace.com – Direct display buys on low inventory
http://www.adxpansion.com/ – Display/banners on adult inventory
http://www.aim4media.com – Display media buys mainly European traffic
http://www.ampkeywords.com – self serve text ads
http://www.bannerconnect.net – media buys/banners, good european reach
http://www.blacklabelads.com/ – Text & banners on adult inventory – adult version of adbrite
http://www.brightroll.com – media buys, banners/video
http://www.cbsinteractive.com/advertise – media buys on very high traffic CBS sites
http://www.criteo.com/ – Retargeting
http://www.directaclick.com – Owned by Fox, media buys, US Hispanic traffic
http://www.directcpv.com – cpv, self serve popups
http://www.ero-advertising.com/ – Web & mobile display/banners on adult inventory
http://www.exoclick.com – Text/display on various inventory. Similar model to adbrite
http://www.filiado.com – Media buys for Brazilian inventory
http://www.glammedia.com – media buys, display, very good inventory for female 
http://www.globalinteractive.com – Smaller scale banner/pop media buys
http://www.harrenmedianetwork.com – Media buys, South American/Hispanic traffic
http://www.hi-media.com – display/media buys, mainly European traffic
http://www.industrybrains.com – now called adHere – text ads on mainly tech sites
http://www.interclick.com – media buys, display, high volume
http://interstitials.net -  interstitial ad network
http://www.intergi.com – banners and static/video in-game adverts
http://www.juicyads.com – Display on adult inventory, flat rate buys per week/month
http://www.linkworth.com – Banners, inline, contextual, plenty of cheap inventory
http://www.megaclick.com – banners on 2 high traffic file share sites
http://www.mirago.com/media – UK/French/German contextual/search ads
http://www.mochimedia.com – self serve in-game ads, 300×250 only
http://www.mythings.com – Retarget the ones who didn’t sign up first time
http://www.neoedge.com – static/video in game adverts
http://www.pamojamedia.com – Adify powered, banners for African traffic
http://www.realtechnetwork.com – Variety of formats, self serve platform
http://www.reddit.com/ad_inq – self serve direct ads on reddit.com
http://www.reduxmedia.com – Display, media buys, some good blog inventory
http://www.retargeter.com/ – Retarget the ones who didn’t sign up first time
http://www.rubiconproject.com – media buys, nice interface/inventory
http://www.salemwebnetwork.com/ – Display ads on Christian website network
http://www.shenetwork.se – Adify powered, target Swedish women
http://www.smowtion.com – display banners, most South American inventory
http://www.snap.com/advertisers – text/inline type ads
http://www.specificmedia.co.uk – Media buys/display on UK/Euro premium inventory
http://www.tattomedia.com/advertisers/ – banners/display/media buys
http://www.trafficjunky.net – self serve display/banners, good volume inventory
http://www.trafficmarketplace.com – display/email ads, media buys
http://www.trafficsynergy.co.za/adrands – banners, South African traffic
http://www.tremormedia.com – media buys, good range of new formats
http://www.unanimis.co.uk – display/video media buys, UK traffic
http://www.utarget.co.uk/v6 – UK display/rich media/video, owned by Fox
http://www.vibrantmedia.com – inline contextual/rich ads, media buys
http://www.xa.net/ – Display/retargeting/facebook ad exchange
http://youyield.com/ – Interstitial full page ads
http://www.yume.com – in-video ads, media buys
http://zedo.com – display/media buys
http://globaltakeoff.net – display/media buys
http://www.gfy.com
http://www.trafficholder.com
http://www.exoclick.com
http://www.trafficjunky.com
http://www.ero-advertising.com/
http://www.juicyads.com/
http://www.adxpansion.com/
http://www.crakmedia.com/
http://www.trafficshop.com/
http://trafficbroker.com/
http://www.etology.com/
http://www.trafficforce.com/
http://www.adultsense.com/
http://trafficmack.com/
http://www.wildlinecorp.com
http://www.chokertraffic.com/
http://www.gtsads.com/
http://www.adultadworld.com
*** Mobile Ad Networks ***

http://www.mobclix.com
http://www.inmobi.com
http://www.admob.com
http://www.quattrowireless.com
https://www.decktrade.com
http://www.jumptap.com
http://www.mojiva.com
http://www.zestadz.com
http://www.buzzcity.com
http://www.huntmads.com