Sinclair ZX Spectrum 128 emulator
Spec128 is a ZX Spectrum 128 emulator for the Acorn. There's currently no shortage of 48k Spectrum emulators for the Arc, but there are only two other Spectrum 128 emulators, and both are commercial. Spec128, however, is freeware. I'm also planning to implement emulation of some Spectrum hardware that no other freeware Spectrum emulator, on the Arc or any other platform, will emulate, most notably the Plus D disc drive interface.