Alcohol 120%, DVD Identifier, DVD Decrypter, IMGBurn, Nero DriveSpeed, and Plextools all have the ability to open/close your drive tray. That's just a quick scan through my start menu, not sure what other apps offer that functionality, nor will I be installing any others as my needs are met.
Note that Alcohol and Nero don't have seperate buttons. Alcohol labels their button as 'load/eject' while Nero just uses the universal eject symbol.
I also have widgets on my desktop to open/close my drive trays.