Eject! is a simple, freeware, program that opens the CD tray on most Macintoshes. It is compatible with all pre-OS X Macs. I wrote it because I couldn't find the official Eject Application from Apple, and I wasn't about to pay $15 for a piece of shareware just so I could use an old keyboard (with the power-key that I need for access to MacsBug) with my new Mac. The C source code is also freely available.
Mac OS Classic
||System 7 or higher