Richard Bannister has updated Genesis Plus to v1.3.1. The sole new feature in this version is support for Game Genie cheat codes. Genesis Plus is a very accurate emulator for Sega Genesis games. If you are using an older machine or you are having speed issues with Genesis Plus it is recommended you use Generator.
Richard Bannister is a popular Mac emulator porter and author, currently maintaining a library of over twenty-five emulators. If you are looking for emulators for the Spectrum ZX to the Virtual Boy, Bannister's site is the place to check first.