(updated December 20, 2009)
ShapeShifter is a Macintosh-II emulator for AmigaOS. It has been superseded by Basilisk II, which also runs in AmigaOS. ShapeShifter's emulated machine supports Mac OS 7.1 to 8.1.
It was written by Christian Bauer.
Official page and downloads are located at Bauer's site. There is also some third party support online (updated circa 1999).