Theres a lot of websites that share ad revenue with the developers. If you make games then submitting to these websites is a must as they bring in a nice extra stream of income, specially if your games get features. So I'll list the best ones I know of and what I've made so far.
This website is a must if you make flash games! one of the biggest flash game sites on the net. They bring in a great amount of revenue. Most of my ad revenue came from The Unfair Platformer here because it was so popular. Games on this website also feature badges. So add the API to every game you submit because this increase your ad revenue by 10% as well as put your game in the running to get badges which will bring in a lot more plays. Your games can also win competitions. If your game gets frontpaged I can garuntee around $20-50 a day ad revenue. Unfortunately smaller games that don't get attention will make only a few dollars total.
In six years Kongregate has made me $4,000
Pretty much the biggest flash site out there. Unlike Kongregate that only takes games, Newgrounds will also give ad revenue for flash movies. Unlike Kongregate the ad revenue is a lot lower and harder to get here, but it will still bring in a decent amount if your game wins awards or is frontpaged. Newgrounds is great if people fan you because all new games/movies you submit will show up to them in there news feed and get you extra views.
In six years Newgrounds has made me $500. Some from ad revenue and some from winning game competitions.
This website Is more newer and I found only a few months ago so I don't know how well my ad revenue will do here. GameJolt is also more focused on Indie games made with full .exe based games. Flash isn't as popular but is still allowed.
So far the website has only made me 87 cents in 2 months. This would be a lot higher for games with more views and non-flash games.
There are others out there, but they require adding there API that which puts logos in there game. I don't really like changing my game logos so I don't use them but they are worth looking up if it's something you don't mind doing.
These websites are just a small bonus that can be made on the side of your sponsorship and main game revenue. Being more active on the websites will also help bring in more fans and attention to your profile and increase future views for games.