check out http://www.metroidmetal.com/songs it has metal remixes of alot of the metriod songs my favs are torvus bog and the tunnel
also try
metroid x the beginning http://www.newgrounds.com/portal/view/186502
metroid x the kombat http://www.newgrounds.com/portal/view/188589
oh yeah and bug the auther to make metroid x 3 it is way over due
project xenocide this is a truly awesome unofficial sequel to the Xcom games it includes next gen graphics and is totaly free...so why isnt it in the best free ware games on the web section? simple its not done yet...how do i know this? well duh it says so on the main page of the site...AND i am developing music for them...thats right i get to say "im a developer for a big ass project" and its true =D ...oh it says its suspended but its not really its just going slow...so join up and start helpin!!! alot of what they need is just simple 2d texture art for items like backrounds/terrain so take ten minutes and draw something will ya? anyways http://www.projectxenocide.com/