This service sends you SMS messages (no more than 2 per month) advertising bitcoin related services, and, in turn, gives you free bitcoin.
FreeCoins
This service pays you a small amount of bitcoin for answering a captcha check.
LegendaryFaucet
This service pays you a small amount of bitcoin for answering a captcha check. (Almost idential to the service above.)
BitSprinkle
Send this bot a message on Twitter with your bitcoin address, and it'll send you some bitcoin :)
VNBitcoin
This service sends you .0005 BTC after you've verified an email address with them. They won't use your email for anything other than verification, so don't worry about spam! This is currently one of the best free bitcoin sites out there.