[McGruff]

This link that a buddy just sent me requires resurrection of an ancient thread. It's an incredible metal version of levels 1 and 3 from the original Castlevania.
www.mediadevils.com/castlevania.zip

 

[MannPower]

As for MegaMan 2, The Megas are a band who've created a 'concept album' about the game's story. Some tracks are humorously cheesy, and others are actually pretty decent (I enjoy 'The Annihilation of Monsteropolis' and 'The Quick and the Blue'.)

Check their site out here. They have a sample player at the bottom of the page: http://web.mac.com/themegas/The_Megas/main/main.html

And their myspace, which has different songs.

http://www.myspace.com/themegas