A few years ago I played Syzygy at a friend's house and had a blast! Enough so that I went out the next weekend and bought a game for myself.
Syzygy is a fast-paced word game. There are over 300 scrabble-like letter tiles (but no point value on any of them). At the beginning of the game they are all flipped over, letter side down. Each player selects 9 tiles and when the game starts makes his or her own crossword using those nine tiles. The first player that does so yells "DRAW" and each player draws another tile (or two, to move the game along more quickly). The players that did not get a chance to play all their tiles simply have two more tiles to add to the ones they are already using.
You can rearrange your tiles around any way you'd like, but you must always create legitimate words. At the end of each round, each player goes around and reads all the words they've created and players can challenge, just like in scrabble. If a non-word is found among the other words, that word and all the others connected to it are removed from the puzzle. The number of tiles left over gets counted for a certain number of rounds, and the lowest score at the completion of these rounds wins the game.
This game can be played with up to 12 players. You can play it solitaire (I've never tried). I have found that you really need more than 2-3 people to make this game fun. With only a couple players, you can frequently find yourself stuck with no one able to make a move.
If you love word games and are looking for something exciting, try Syzygy. It is a little pricey, but very fun!