Hi,
I'm working on a widget that allow Android developers to get and show ads from another ad distributor in US. It can be used by itself, or with AdMob -- one is used as backup of another. This distributor payes better per click (sometimes much better) than AdMob. I'm not ready to release it yet, but if you or other developers interested to be beta user, I can send you something in next couple days or so. At least you could get a feel on how much they pay. You'd need to get an account from them similar to what you do with AdMob. I will not take a cut of your ad revenue.
Oh, very important -- they don't pay you if a click comes from outside US. So there's no benefit if most/all of your application/game users are not in US.