We own a network of 336 Yahoo groups with 300,000 members. Will this work for you? i can send you details about it.
Hey i have a site called GGNShare - http://ggnshare.com. It gets a daily of 1000 UV i can offer you a header for just $5.00 per 2 weeks or $10.00 for a whole month. Its growing every day. its a webmaster community site run by phpfox. It has its own forum that contains topics and downloads for warez as well.
My site has more than 30 k uniques per month& 2500 member and is alexa 200 k this week .. only $ 15/mo for two ads. one in the homepage ( banner 468 * 60 ) the other ( wide skyscaper )is in the subpages ( not rotative ) pm me for traffic proofs or anybody intrested . " This sale is only available for 3 days from now "
I have a website which achieves in the region of 7,000-9,000 unique visitors per day. 800,000 - 900,000 page loads per month and currently 2.5 million adsense impressions per month. If you're interesting in advertising on my website please let me know