I've been mildly addicted to playing Words With Friends lately. It's essentially a smartphone/iPad equivalent of Scrabble. At any given time, I'm in the middle of games with five or six different friends. It's interesting to see variations emerge in the ways different people play, and it's fun even when I'm having my ass handed to me (as a couple of my friends do on a regular basis).
It could be better with some variations, though. For example, games with more than two players would be nice, though I suppose it's possible limiting the game to two players may be one thing that keeps the game from infringing on Scrabble's trademark.
Mostly, however, I want dictionary editing options. Braz tried to play "oxen" the other day, and the game told him it wasn't a word. Um, yes it is! I'd like to see, for example, an option to submit a word to the other player(s), possibly with a note of explanation -- if they agree it's valid, then the word can stay; otherwise, the play counts as a pass. Yes, it's a system that could be abused by the approving player, but they might want to submit words of their own at some point, so they'd have to be careful.
And it could make for theme games that ignore the usual rules: allowing the names of famous people, for example. Or permitting fictional words from your favorite sci-fi and fantasy franchises, say. (I want to watch Braz and Jeremy go toe-to-toe on a Lord of the Rings game, right now.)