So, I was thinking the other day "You should make a list of your favorite game music!" Then I sat down and realized that it is actually a fairly hard kind of list to make; when you think back and try to make a list like this, not a lot of music will really stand out.  In my 20+ years of gaming,  I have heard a huge amount of music, but not much of it stands out among the pack.  It took a long time to come up with a top ten list, but then I lost it, so here I start over.  Not in any particular order.
 

1. ' Omen' - Xenogears -  Such a dark and brooding song, It really gives the sense that you are somewhere ancient, forbidden, but you have to push forward.  Such a powerful song.
2. ' The Normandy Reborn' - Mass Effect 2 -  When this song played the first time I got to this point in ME2, it was such an "Oh hell yeah!" moment.  Combined with the visuals of the Normandy SR2 being shown for the first time, and the still lingering impact of the first Normandy getting destroyed, it was one of those hair on the back of you neck standing on end moments.
3. 'Schala' Chrono Trigger - Schala is such a tragic figure in Chrono Trigger; she knows what her mother is doing is wrong, but she has no choice but to help her achieve her goals.  The song is very haunting, and really helps portray the emotion of what is happening to her.
4. "Dark World' - Legend of Zelda:  A Link to the Past - Just when you though you were going to save Zelda just in the nick of time, you arrive just a moment too late,  After coming out of top of the man you thought was responsible for everything, you get sent to the Dark World.  The first time you hear this song, you feel even more resolved to fix everything that has gone wrong.
5. "Phendrana Drifts' - Metorid Prime - Living in parts of Canada that regularly get large quantities of snow in the winter, when I first heard this song, it just felt right for the snow covered Phendrana Drifts. Really cool song to listen to when driving through a snow storm.
6. ' Theme of Samus Aran: Galactic Warrior' - Super Metroid - As ridiculous as the title of the song is, such a great peace of music.  You first hear this after descending into the caves of Zebes as far as you can, and then climbing your way out. Just as you get out to the surface, this triumphant piece begins, and you think 'Hot damn, if I could do all THAT, then nothing is going to stop me now.
7. 'Dream of the Shore Near Another World' - Chrono Cross - Yasunori Mitsuda really outdid himself with the soundtrack for Chrono Cross.  His previous two major soundtracks (Chrono Trigger and Xenogears) both had elements of what would be in this game, but when they combined, they created something truly memorable.  Say what you will about the game and it's story, the best part of it was the diverse collection of great music.  It is hard to narrow down just one song that I want to put on this list, but this is by far my favorite.
8. 'Undersea Palace' - Chrono Trigger - I wanted to keep this list to one song per game, but hearing this song again reminded me that I HAVE to put this on here.  Very few songs give the sense of 'Things are getting really bad and time is running out" the way that this song does.
9. 'Hollow Bastion' - Kingdom Hearts - Kingdom Hearts was an interesting game to me, It combined the Disney movies of my childhood with the games of my high school years.  This first part of the game seems like a fairly lighthearted trip through the many world of the Disney mythos, but at the halfway point, you start to see just how dire the situation is, and just how much chaos has been wrought by Maleficent.  When you get to her base of operations at Hollow Bastion, you have just been betrayed by your best friend, and you still must press on.  Because the music of the game up until this point (except the intro) had all been remixed versions of music from Disney movies, they really did an excellent job making music for this area that didn't sound out of place.
10. ' into the Thick of It' - Secret of Mana There is a lot of great music in Secret of Mana.  Dark Star, The Mana Forest, the last battle theme, all of these are great, emotive pieces of music, but no other song brings me back to the days of playing this game with my brother back before I started high school like this song does.