On the iPhone I have Skater Nation, which is easy to play like THPS 1 and 2, but the characters are so obnoxious it's almost distracting. Sill though, it's easy and good for little bits. I got Mive V's game from the app store when it came out, and I'm digging it as well, I just have to have more time to kill to play it. It's pretty sick because you have to push, and I like the way you slide your thumb around to do tricks. I'm still getting used to the way it works with the accelerometer, as you have to really turn to turn, vs. SN where you turn with a little virtual touch pad. Both are good time wasters, but SN's intro takes for fucking ever, and there's only a milisecond chance that lets you skip it (like forwarding a video).
Besides that I play Counterstrike Source, but barely. I'm grimcity on there, I play random servers, usually the ones out of Texas with the good ping times.