I know these are a bit cliched, but I haven't seen anyone else mention them:
The Burning Plague (available free on WotC's site) is short but fairly good. Adding a few adventure hooks here and there can make this a good starting point for a new campaign.
Gorgoldand's Gauntlet (available a while back on a CD packaged with Dungeon magazine) was fun, IMO. There are a few more built-in adventure hooks in it than in The Burning Plague, but at least one of the puzzles is a bit silly and you might want to tweak the treasure a bit.
The Sunless Citadel (WotC published adventure) has received mixed reviews, but I'm kind of fond of it. If your FLGS allows, read through it once or twice before you buy. It's probably long enough to last a 1st level party for a few sessions and provides loads of opportunity for placing adventure hooks of your own. And, yes... Everyone loves Meepo.
Dungeon has also published a few adventures in the Challenge of Champions line that were entertaining for groups of puzzle-solvers. I found that using one of those was the best way to introduce a new player to the group and the fastest way of getting a new party together without resorting to the old "you meet at the inn around a tankard of ale and decide to adventure together" cliche. These work especially well if the players haven't played in your game before and actually fear the traps/puzzles. If you use these, though, be aware that there were misprints on two of the puzzles in the last one Dungeon published. Try to track down the adventure before that, if you can (I think it was Challenge of Champions IV... It was the one with the "TICKPOLE" puzzle at the end, and the robot on the cover of the magazine, IIRC). It was way better than the last published one, IMO.
Hope that helps.
