The only soundtrack i own is form the Australian movie "Romper stomper" (starring Russell Crowe). The lyrics are pretty weird but the songs rock!
But there are several movie themes I like. I don't know if they have a special name so I'll give you the names of the movies or series:
The Godfather (the violin song)
Forrest Gump (the song played on the piano at the end of the film)
The good, the bad, and the ugly
Once Upon A Time In The West
A Fistful of Dollars
M*A*S*H
Platoon (Adagio for strings)
Full Metal Jacket (The song in the intro where everbody get their heads cropped)