Regarding GAMERA 3, there are two bonus tracks (Theatrical Trailer BGM part 1 and Theatrical Trailer BGM part 2) on disc 3 of the CD set GAMERA 1995-1999 ULTIMATE SOUND TRACKS. These tracks are not on the regular release of the GAMERA 3 OST.
I think you can find all that you want and more than you want to know .
The track for Fellowship of the Ring (well, the one most people want) is "Gothic Power", , well, you might get lucky!

One of my particular favorites which seems to be undergoing a resurgence lately (most recently the trailer for SYRIANA) is "God Moving Over The Face Of The Waters" by Moby. Of course, Moby get's a lot of his stuff used for film and commercials.