Versatile Commodore Emulator
VICE is an emulator collection which emulates the C64, the C64-DTV, the C128, the VIC20, practically all PET models, the PLUS4 and the CBM-II (aka C610). It runs on Unix, MS-DOS, Win32, OS/2, Acorn RISC OS, BeOS, QNX 6.x, Amiga, GP2X or Mac OS X machines.
Jainja is a JVM (Java Virtual Machine) written in Java
Spice+ is a general-purpose circuit simulation program, based directly on SPICE 3F.5 from the University of California (Berkeley). An improved version of Spice for DOS, Windows and Linux. http://spicep.sourceforge.net