MESS (Multi Emulator Super System) is a project which documents the hardware for a wide variety of (mostly vintage) computers, video game consoles, and calculators through software emulation, as MAME does for arcade games. As a nice side effect to this documentation, MESS allows software and games for these hardware platforms to be run on modern PCs.

As of version 0.142, MESS supports 555 unique systems with 1,460 total system variations and is growing all the time (you can find a complete list of the supported systems here)