It seems like the simplest games are usually the best suited for Android (or maybe it's the other way around). If you take a look at the most popular games in the Android Market, they are almost all strategy-based, or very simple action games. The last four games I have downloaded to my phone are no exception. Here's a preview of each of them:
Fruit Ninja - In this game, you basically use your finger as a sword to slash fruit that floats into the screen by swiping your finger across the screen. You have to slash as much fruit as possible before you either miss three fruits, or slash a bomb. You can unlock different swords or backgrounds by accomplishing different tasks. As I said above, it's fairly simple, and can get very addicting. This is also an OpenFeint game, which is basically a social gaming platform. It's only $0.99 on the Android Market. Check out Fruit Ninja at Appbrain.
Flick Kick Field Goal - This is another OpenFeint game with a simple premise. Basically you use your finger to kick a football through a set of goalposts by flicking your finger across the screen. The game makes you kick from different positions, with different wind speed and direction. Again, a very simple game that becomes very addictive. It's fun if you have a few moments to kill while waiting in line at the DMV. It's $0.99 on the Android Market. Check it out at Appbrain.
iBasket - I guess this game was fairly popular on the iPhone and the developers have decided to port it to Android. It's another simple game where you have to make as many baskets as possible within a 90 second time-frame by selecting the basketball with your finger and swiping it toward the basket. The only gripe I have with this game is that an advertisement sits at the bottom of the court, which can interfere with gameplay. I know that the developer is trying to get more click-throughs on his ads, but this isn't the way to do it. Developers, if you want a good example of advertisements that are well placed and don't interfere with gameplay, check out Fish Food. If you want to try out iBasket, download it for free from Appbrain.
Kamikaze Race - This is probably my favorite game out of the bunch. The title best describes the game - you drive your car at increasing speed with no brakes down a traffic-packed highway. You steer your car by tapping on the left or right side of the screen to try to avoid other cars (the game is currently in beta so there are some bugs - the virtual buttons at the bottom of the screen don't work, but you can tap the screen above them and it works fine). The longer you go without crashing, the higher your score. I can't stop playing this one. It's free and I highly recommend downloading it.
Let us know in the comments if you have any other game recommendations that we should give a try!