Chris Smolinski of Black Cat Systems has released Sara 0.5.0, the only known Apple III emulator in existence. The BCS site contains a link to the required ROM and a collection of disk images to get you going.
The Apple III was supposed to be the successor to the Apple II, but bad marketing decisions, engineering flaws and continued strong sales of the Apple II eventually doomed the Apple III line. It does have limited Apple II compatibility, so it wasn’t all bad. The Apple III, and III Plus did find their niche in some places, and even today, enjoy a dedicated retro-computing following. Apple III collectors love their machines.
This release is a Universal Binary for Mac OS X.
Update: Sara 0.5.1 released 05/23/08.