Free Unix Spectrum Emulator (Fuse) 1.0

Fuse (the Free Unix Spectrum Emulator) was originally, and somewhat unsurprisingly, a ZX Spectrum emulator for Unix. However, it has now also been ported to Mac OS X, which may or may not count as a Unix variant depending on your advocacy position. It has also been ported to Windows, the Wii, AmigaOS and MorphOS, which are definitely not Unix variants.