Dave and I rented the GameCube version of Return of the King yesterday.  It was really awesome.  For someone really looking forward to the movie, it really heightened the anticipation.  It follows the storyline from the end of Helms Deep through the end of the movie (I guess, we didn't finish it by any means).

If you are a fan of the old Gauntlet arcade game, and a fan of the books/movies, it's fantastic.  It does contain real shots/environments from the movie, so if you're looking for that sterile movie experience, don't play it until after the movie, but this is such a well-known story that it shouldn't matter much.

Anyway, it's real cool, and has a nice multi-player cooperative mode.  I've heard the PS2 version doesn't look as nice, but should be pretty cool as well.