JBit is small java application for mobile phones (MIDlet) that gives you a programmable 8-bit microcomputer. With JBit, you can edit, save, run and debug assembly (6502) programs directly on your phone.
NEmu is an emulator/simulator for exploring computer architecture. It
provides a virtual machine, a debugger, and simulations of various cpus
and hardware. NEmu is built on top of ALib, my own application framework.
Softx86 is a library that provides software emulation of an Intel 80x86 CPU. The library takes care of executing opcodes and handling exceptions while the host application is responsible for providing simulated RAM, I/O devices, external signals.