A nice posting over at Greg Costikyan's Play This Thing alerted me to the 2010 One Page Dungeon contest.
There are a lot of entrants, and I'm not really much of a tabletop RPG player, so most of the entries went over my head, but I did rather enjoy reading through the nicely formatted PDF collection of the 2010 winners.
Personally, I liked "Trolls will be Trolls", "Velth, City of Traitors", and "Mine! Not yours!" the best, though all of them were quite nice.