See also:
Best VGM 304 - http://www.youtube.com/watch?v=KrvdivSD98k
Best VGM 580 - http://www.youtube.com/watch?v=CNUgwyd2iIA
A collection of my favorite videogame music. Note that most of them are from games I played so I might miss some great ones from games I never played.
Genesis
Sonic the Hedgehog 3
Hydrocity Zone Act 1