I love oldschool chip tunes. If you were playing games in the 80 chances are you do to. At least for nostalgic purposes.. 
 
I would like to recommend www.machinaesupremacy.com if you also like metal music. They are a band from Luleå, Sweden that plays SID-Metal (SID was the music chip of the C64) 
 
If you just like the old school chip tunes raw you should check out Linus Åkessons Chipophone which is his own creation. An instrument to play chip tunes live! Check it out for some classic tunes!  
Presentation of the Chipophone http://www.linusakesson.net/chipophone/index.php  
Spellbound theme by Rob Hubbard performed on the chipophone  http://www.linusakesson.net/chipophone/spellbound.php

Or just go to SlayRadio for some awesome chip tunes and remixes, as well as Remix 64.