I’m currently addicted to Swipe Four, an iPod/iPhone game. You can try it in your brower for free here, and it’s on sale in the App Store for $1.99, easily worth it if you like word games.
Make four letter words until you’ve filled the four by four grid, then move on to progressively harder levels (seriously, what am I supposed to do with three Y’s and a K?) I made it to 40th on the leaderboard one day, but it’s not unusual I get the message “You’ve placed 1,855th!” Like I’m supposed to be proud of that.