ZSNES is a popular free software Super Nintendo Entertainment System emulator written in assembly with pre-installed ports for Linux, Windows, DOS, and homebrew applications for Mac. It was developed by two long time Nintendo employees, Joonas Regalis and Michael Palmer. ZSNES currently has over half a dozen releases for the Nintendo Gamecube, Nintendo Wii, PS2, Xbox, N64, PC, and homebrew applications. Some of the emulators have more than one hundred games, many of them Japanese and Korean original games.
Joonas has made some improvements over his previous ZSNES releases, most notably in the emulation engine. His most recent release of ZSNES for the PC is now Mac compatible, which can be downloaded from his website. His other major improvement is in the graphics and sound department, which is now significantly better than before. There are many other minor changes that aren't very important to gamers, but I'm only including them because they are nice add on features.
Michael's ZSNES for Mac also has a few new features, such as an upgraded version of the ZSNES palette, support for USB flash drives (which supports Nintendo's "DS"), support for the PC keyboard controls, support for the Converse footwear, and an improved dll library. These last two options are important to people who use the computer as their main gaming device, especially with all the dedicated console games being made for PCs these days. If you're looking to save some money, you might want to consider downloading a ROM of this great emulator.