Ascended M.U.G.E.N

This was a list I once posted on Infinity, and it grew. And I must thank The Dude Z there for reposting the list after Infinity went through their forum reset. I've also posted this at the Guild, and I thought this may be of some use here as well.

Galbadia Hotel - a humongous archive of video games and anime music. Many hard to find tracks are present here, plus if you register a free account you can download some of these soundtracks in a packed form instead of the usual track-by-track method.
http://gh.ffshrine.org/


kingdom Hearts Insider - seems to contain all that Galbadia Hotel does, plus, since GH tends to be unavailable to US users from time to time, it can be pretty useful.
http://downloads.khinsider.com/


The Protoman Homepage - what started as an archive of MM music and went through date-limited download selections due to limited bandwidth, has evolved into a pretty nice little video games music repository.
http://music.quandra.org/Music/


Home of Snes - an archive of music from the Snes, standing for Super Nintendo Entertaining System, or Super Famicom in Japan, console. Everything is in SPC format, so you'll have to install an SPC player or plugin to play them.
http://snesmusic.org/


Zophar's Domain - A huge site about emulation of multiple platforms on multiple platforms. But what interests us is that it has a Video Game music database with soundtracks in respective platforms' formats, plus it also contains various players and plugins to play these.
http://www.zophar.net/


Home of the Slog - a little site containing the tunes used in the smash-hit flash series 'Madness' made by Krinkles. Some of these tunes are simply amazing.
http://slogcorp.com/music/


Newgrounds Audio Portal - the audio section of Newgrounds, the ultimate Flash movies portal. Contains uncountable numbers of music composed/created by whoever wants to post it there. Some of these are really awesome.
http://www.newgrounds.com/audio/


Mark Knight's Game Sounds - an archive of works by mark Knight. Some of these are cool, but I especially like his arrangements of the tunes from Duke Nukem 3D.
http://www.gamesounds.co.uk/downloads.html


Sectionz Music - Both of these are the home of many, many musical acts that are overwhelmingly.
http://www.sectionzmusic.com/


Wire FM - deserving of record labels. Be sure to check out Splinter, Deadmau5, Error, and many more!
http://www.wire.fm/


Tefnek - Need a breaks fix? Tefnek is your boy. He's got some really original sounding stuff.
http://www.tefnek.com/


Beatport - Down all the hottest electronica, acid, progressive, etc tracks here! An unbelievable collection.
http://www.beatport.com/


Atomic Fire - a nice selection of Megaman themes, amongst other MM themed stuff.
http://www.atomic-fire.com/


OverClocked ReMix - features a bunch of remixed game tracks.
http://www.ocremix.org/


purevolume - if you're into listening to music not from a show or game, it has a nice selection. Good interface, free to use, offers downloadable tracks, lyrics and more.
http://www.purevolume.com/

Blue Laguna - Features music from a number of RPG's. There's even the options of previewing the songs before downloading.
http://www.bluelaguna.net/

VG Music
www.vgmusic.com

Shadowhaxor -Although, at the moment, the selections isn't as great as, say, Galbadia Hotel, they offer full soundtrack downloads. (registration is needed)
www.Shadowhaxor.net

OverLooked Remix
http://olremix.org/

MegaDriver
www.megadriver.com.br

Dwelling of Duel at VGMix
http://dwellingofduels.com/all/

Minibosses
http://minibosses.com/

Metal Slug Database
www.mslugdb.com

Dwelling of Duels - A site where VG-remix competitions are held. Old submissions are downloadable.
http://dod.vgmix.com/

Project 2612
http://www.project2612.org/list.php?page=all