A Bitcoin faucet is as site that despenses Bitcoins to a BTC address for absolutley no cost!
How do faucets work? A user goes to one of these many "faucets", enters his or her BTC address, usually completes some sort of anti-spam act, and clicks a button to recieve the Bitcoins! Mos of these Bitcoin faucets can be visisited on a certain timeframe such as every hour. Faucets record the user's IP address and Bitcoin address so that one user is not draining the "fountain" that stores the Bitcoins.
Faucets like these will continue to operate and if visited frequently enough, can result in quite a big payday.