TagMan is a web-based version of the folk-game Hangman. This seems completely unremarkable until you consider the game's near-endless supply of words consists of the most popular tags harvested from Technorati, Del.icio.us, Squidoo, or Flickr.

Fastr is a guessing game using Flickr images. The object of the game is to review ten images and decide what tag they all have in common. You can compete against other live players--the fastest guessers score the most points.

TagMan and Fastr represent an ingenious use of freely-available people-power, perhaps inspired by The ESP Game, a Carnegie Mellon University project launched in 2003. The ESP Game actually helps to build a growing (and increasingly-accurate) database of labelled images through its game-play, which involves two players who can't communicate with each other choosing matching labels for the same image.