Linux Hard Disk Cleaner

Is there such a thing?
An equivalent for CCleaner and other such programs on Linux? I know it's more secure, but there's still crap to delete.

>>3
$ shred --help
Usage: shred [OPTIONS] FILE [...]
Overwrite the specified FILE(s) repeatedly, in order to make it harder for even very expensive hardware probing to recover the data.

*nix much ??