I've done extensive comparisons between ADbrite and Bidvertiser.
Bidvertiser: Forget about it unless your page their ads are on, is getting at least 20,000 page views a day. Reason is because their CPC is way too low. But increases up to 7 cents average at 15,000+ pageviews.
Etology I found actually equal to Adsense, but only on a very high traffic page that gets us 70,000+ pageviews a day. Their payments for NOW can be delayed up to 3 months, so you won't see their earnings immediately on your account. They pay via PayPal.
All in all, Adsense is king still.