I usually spell this as !!:gs/foo/bar/ (in bash). Is there a functional difference?

! command history can also take line and word selectors. I type something like !-2:2 surprisingly often.

Anybody else remember Haibane Renmei? or (more depressing, but less sad) Wolf’s Rain?

If you have ever used an HP RPN calculator (which are clearly the best calculators), there is Droid48, which emulates the HP 48GX.