I'm not very familiar with music theory (though I'd like to study it someday), but I find some of the older chiptunes quite entertaining to listen to, with
Cloudcones by Zabutom and Nagz one of my personal favorites. I love the change in direction the song takes at 1:35 and 2:15.
EDIT:
Another one of my favorites is Jake "virt" Kaufman's FM-synth jazz tunes,
Kawk. Oh, and Kaufman's VRC+FM-synth remix of
Love Foolosophy is another one of my favorites too.