byuu on the forums pointed out an update to the popular Super Nintendo emulator Snes9X. This open source emulator sports incredible compatibility and has been the most popular Super Nintendo emulator for Windows and Mac for years. This update includes a large amount of bug fixes, an updated sound core, and some Leopard and Snow Leopard specific changes.
While Snes9x sports a must faster emulation core, if you are looking for cycle-exact emulation try out Richard Bannister's BSNES.