Emulator of the HP 48 scientific calculator, using RPN. Port of the X48 project (sources available on github). HP48's "grayscale mode" cannot be emulated. Visit www.hpcalc.org for a large program collection. Cool tip: tap the HP's LCD to show/hide a simpler numeric pad !
Famous C64 emulator, ported to Android. Sources are available on GitHub, search for FrodoC64.
Amiga emulator, based on UAE4All. You need a ROM copy of your own Amiga ! Touch screen or trackball as mouse control.