Ant Movie Catalog is a free (really free, i.e. the source code is available) program made to manage your collection of movies on DVD, CD (VideoCD, DivX, ...) and tapes.
Browse the links above this text to get more information and download the program.
If you use GNU/Linux rather than Windows, you can try to use WinE to get this program running; some people notified me that this was working. You can also check Moviefly, which is a complete rewrite of Ant Movie Catalog made with Python.
If you search for a program to catalog other things such as books, audio CDs or games, I recommend to check the "Mods" section of the forum where you'll find modified versions of Ant Movie Catalog. For games, a new program derivated from Ant Movie Catalog is under development: Sisimizi Game Catalog; for the moment a "preview" version is available from this thread on the forum, comments are welcome.