How to find advertisers for your site?

I want to set up a self-service advertising platform on my social website. I'm hoping that as web traffic picks up, users and advertisers will advertise on my site. How can I find more advertisers to advertise on my site at the initial growth phase? Is there a service that lets you advertise your site to ad buyers so that they can notice your site and advertise on your site?

I'm trying to find more advertising revenue besides Google Adsense.

Why don't you start off with Google AdSense and find out which companies are advertising on your site through AdSense. You can then contact them and ask if they'd be interested to use your self-service platform instead of going through Google.

I've seen:

http://buysellads.com http://fusionads.net/ http://decknetwork.net/