You could have a field day with Earthbound. If songs aren't being directly sampled, then they're being musically parodied... I'm sure everyone knows about Earthbound though :3 wonder if The Beatles ever found out about it... and the countless other artists that got referenced, ha.
Oh, I made these mp3s a couple of years ago, might be sort of interesting/relevant!
http://www.shakal.net/lunar/temp/vgmalikes
1. Sim City vs. Link's Awakening
2. Kaeru no Tameni vs. Link's Awakening
3. Super Mario 64 vs. Donkey Kong Country 3
4. Sonic the Hedgehog MS/GG vs. Twinbee Rainbow Bell Adventure
5. Secret of Mana vs. Sakura Relaxation
6. Secret of Mana vs. Sora no Iro Mizu no Iro