EduMIPS64 (aka edumips) is a cross-platform MIPS 64 ISA simulator. It can be used to run and debug MIPS programs that are written using the MIPS64 instruction set. It supports visual debugging and lets you see what instructions do in the pipeline.
Dioscuri is an x86 computer hardware emulator written in Java. It is designed by the digital preservation community to make sure that documents and programs from the past can still be accessed in the future. Dioscuri is durable and component-based.