If you want to monetize from a game you have developed, apart from adding MochiAds and submitting your game to MindJolt as I did with La Cucaracha, you can look for a sponsorship.
There are many games portals out there that, if your game is good, would be happy to pay you some money if you change/add this or that to your game, however, the best deal I have found so far is the Hallpass Developer Top Score Special.
The idea is to make your game compatible with their top-score system and you do that adding just one line of code.
I added this line of code to my game Slippery Pong and submitted it to Hallpass, when my game was accepted and added to the portal, I've got an email from Hallpass letting me know the $50 had been paid to my paypal account :)
Bill, from Hallpass says:
...I have been a full time web master (for games portals) for almost 10 years now.
The reason why I have been able to stick around this long is because I "work with" developers. Not simply sponsor games which I think will get the most hits back to hallpass. As you can see many of our games get passed up by other portals, on hallpass I try and work with up-and-coming developers in the hopes they remember us after they make their first big hit and allow us to work with them on it. I dont get the max value of every game I sponsor but when you add up all the developers together hallpass offers a great package, and helps promote unknown talent.
Hallpass allows your game to have MochiAds so you get money from both your adds and from their sponsorship. I think is a great deal!
Now go and check out Hallpass and don't forget to vote for Slippery Pong ;)