sinjin - This only works on non-journalled drives, but if you change the command to fsck -fy it will check it anyway.
Other fun terminal command thread found previously on ehMac:
You can also try out (use man pages to find out more; in Terminal type in man command
cal -> Shows a calendar.
banner -> Make a banner.
smbclient -M destination -U username -> Send Messenger/WinPopUp messages to Windows computers on your network. Destination is the computer name, and Username is your name (or whatever you want, eg. God.)