If you have a Mac and can't recall your password, Mount the drive as a firewire drive and from the terminal of the other computer type

strings -8 /Volumes/MyOtherComputer/var/vm/swapfile0 |grep -A 4 -i longname
And you may just get your password shown back to you in plain text. This works in 10.3.4 and below. As Jason has found out, if you have lots of ram, you don't get a swapfile, therefor your passwords are not saved in plain text.

Of course there are less friendly uses for the above command, but I'll leave that up to you to figure out :p