Me, I'm on the two geo games- Defense and Swarm. Great tower defense games that are simple to pick up, but can be surprisingly challenging at times. swarm was a pretty innovative take on the first one, with the "hive" setup.

The other one I picked up recently is "Cartoon Wars: Gunner" or something to that effect. I sort of ruined it when i said to hell with it and bought like 250k in gold for like $4 in real money.