What isn't available for Linux these days? After a quick search around the net, i've found emulaters for most of the popular consoles on Linux! Some of which are my favourites on Windows, whilst others I've never heard of:
ZSNES (Super Nintendo) - Just as compatible as the Windows version, however i've noticed a few sound clitches
DGEN (Sega Genesis) - Never heard of before, but I gather it's been discontinued for some time
Generator (Sega Genesis) - Never used this one before either
ePSXe (PS1) - I was mighty suprised (and very happy) to see a Linux port of this emulator. IMO it's the best PSX emulator there is!
VisualBoy Advance (Gameboy Advance) - Probably the best Gameboy Advance emulator available on Windows. I hope the Linux port is just as good
Mupen64 (N64) - Never used before, but I gather theres a lot of work still to be done
All of these emulators are available for download in source code. However there a loads of RPMs around as well.
Please remember you must own a copy of the game and console if you wish to play them on your PC.