Two Steps From Hell is a group known for creating music to use in movie trailers. Their piece "Freedom Fighters" was used in the teaser trailer for JJ Abrams' Star Trek revamp, "Protectors of the Earth" was used in the trailer to Inkheart, and recently, their "Am I Not Human" can be heard in the trailer to Tron Legacy.
Recently, they released an album available to the general public, "Invincible". You can find it on Amazon.com, iTunes, and CDBaby. It includes the above pieces and this really amazing composition.
Amazing that they only do music for movie trailers, a score like this would be brilliant for a full length motion picture.
*edit* I forgot to mention, the name of the piece is called "To Glory"