Hy'all

Password protection often relies on hashes. If you don't want to save a password in clear text, you save it's hash, when one of the hash's qualities is that you can't get from the hash to the original password, so in order to crack it you would need to either use dictionary attacks or brute force your way through all existing passwords... well - not any more!
a (not that new) project called rainbow tables has done all the computing stuff for ya and now all you need to do to crack a password from it's hash is to lookup these tables and find it. it's hundreds of times faster and quite easy to use.
check it out: http://www.antsight.com/zsl/rainbowcrack/