Michael showed me a cool tile puzzle/game today called Tantrix. Despite the name, it has nothing to do with sex; it's a set of pleasingly solid black plastic hexagonal tiles, each of which has three curved or straight lines in three different colors. You can use them for an interesting series of puzzles, or you can play a multiplayer game using them.
You can theoretically buy the "game pack" from
Cherry Games, only they don't currently have it in stock Serious Puzzles [This link added much later. I'm baffled about why I originally linked to Cherry Games; I bought my set from Serious Puzzles. I should also have noted that although they do sell the game, Cherry Games appears to be primarily a seller of sex-related games, and their site is probably not work-safe]. But if you're interested in trying it out online, you can go to the Tantrix site in a Java-enabled browser and play against either a robot or other humans.
I've only played it once, against a robot; pretty cool, though a little hard to figure out the interface. (Hint: after placing a tile, you can click it to rotate it. Your move isn't confirmed until you click the blue dot in your "hand" area where the tile used to be. Another hint: you can use the arrow buttons at the bottom of your "hand" area to step back through moves and see what exactly the robot did. A third hint: a colored dot on a hex in the play area indicates a forced move for the player with that color; if that player is you, a little black arrow appears next to each tile you could play in one of the open forced-move hexes. See the rules for more info; there are aspects of the forced-move rules and the can't-play-in-some-hexes rules that probably aren't obvious.)