Today I added a QCViewMBS class to my plugin collection which allows you to play Quartz Compositions in a REALbasic window on Mac OS X 10.4 and newer:
If you run "locate .qtz" in the terminal, you'll see hundreds of Quartz Compositions. Apple is using them a lot in iChat, iMovie, Photo Booth, iDVD and screen savers. So take a look in this folders on your hard disc:
And don't forget to install Developer Tools to get the Quartz Composer application.