I have had a long obsession with emulators. I have on my system an unfinished emulator for a non-existant computer. I designed a 6502 based computer, wrote the beginnings of an emulator (not all the display modes and sprites I wanted to add yet, but enough to get text on the screen and read the keyboard), then started writing a BASIC interpreter for it in 6502 asm. It actually got quite far (you can write simple BASIC programs in it).
Also, I have an unfinished Arcadia 2001 emulator written in 68020 assembly. Thats pretty cool. You can just about play the "3d" bowling game in it. Most games show bugs, though :-(
Before that I wrote a games console emulator for a non-existant games console (spot the theme ;-) ). I wrote a tron lightcycles game, a space invaders game, and most of a boulderdash engine for that.
I've never released any of this, although some of my friends have seen them. They were all just for fun, anyway.
