In 1983, Parker Brothers issued a press release with advertising an Atari 2600 game based on the classic J.R.R. Tolkien fantasy series. The game was to be called Lord of the Rings: Journey to Rivendell. The player controlled the series protagonist, Frodo. The objective was to guide the hobbit from the Shire to Moria, avoiding Black Riders that plague the troubled land along the way. There were over 2000 screens for the player to fight through. The game was programmed by Mark Lesser (from Frogger II fame, in a time when games could be and were programmed by individuals).
Unfortunately, the game never came to be. We know that prototypes of the game boxes and manuals were created, but the game was never released. Parker Brothers claimed the game was sold out but that was just a cover-up.
Flash forward to 2001. A prototype box is sold on EBay, most likely a display-only unit for the CES shows. The Lord of the Rings series' first movie is scheduled for release on December 19. And, also in December, with remarkably good luck and timing, the retro-gaming fansite AtariAge discovers a prototype of the game and releases it to the public. LOTR fans rejoice, retro-gamers rejoice, and the peons are happy!
See http://www.atariage.com/features/lotr/ for more info on obtaining the game and playing it with an emulator. Screenshots of the game and pictures of promotional items are also available.
Sources: Slashdot for pointing it out and AtariAge (www.atariage.com) for nearly all the relevant information.