There are a number of decent ad networks out there, but there are a bunch of crappy ones as well. You can't go wrong with Google, Yahoo, or MSN. I'm just starting up an ad network myself. It's called Contexaclick. If you wanted to give that a shot, I'll walk you through it myself. Good luck.
Google is a good as well as others such as adbrite and textlinkads. Like turboface im creating an advertising network myself too which will be launching on 1st July where you will be hearing a little bit more about it in the coming weeks to the launch date of the ad network.
here is 10 "top" ppc companies, here is a list; Google 650-330-0100 Overture/Yahoo 503-615-3602 or 866-924-6676 LookSmart 877-512-5665 or 415-348-7842 7Search 773-283-0086 Enhance 800-840-1012 Miva/FindWhat 877-274-2525 Kanoodle 877-526-6635 Search123 818-575-4500 BrainFox 646-223-1255(fax only) SearchFeed 866.722.9951 411Web Turbo10 (UK): 0044 20 7232 1733 Mirago +44 (0)1420 592323 Mamma 888-844-2372 QuePasa Lycos 781-370-2664 Ask/Ask Jeeves 510-985-7400 Bidvertiser 866.319.0373 Go Click 702-784-1787
If you have cash to burn & learn then definitely adwords and yahoo as stated above. Some of the smaller ones just don't seem to convert as well.
I can confirm that the majority of those listed above ar mainly bot traffic. None of them come close to even touching Adwords or YSM for quality of traffic.