It would be unfair to mention the free Magical 8-bit Plug-in without acknowledging who created it: the insanely talented Japanese chiptune band, YMCK:

YMCK Official Site [English]
YMCK Events [Japanese]
YMCK @ Myspace

And, most importantly:

YMCK Music Videos @ YouTube

Their style is a unique mash-up of the tightly-quantized, hyperactively cheery iconic Nintendo music with even more densely-packed jazzy harmonies than Mario could muster. It isn’t about gimmick: this sounds like someone who was practicing 8-bit at age four the way some people practice violin. Or, as they put it:

While the sound is cheap, the song compositions are influenced by jazz from the 1950’s and 1960’s, with a clear and feather-light 4-beat rhythm underlying sophisticated harmony progressions. The experimental combination of these two features has resulted in the unique YMCK sound, which is neither techno music nor jazz. YMCK uses limited 8-bit sound to take you out for dreamland.

Yeah, pretty much that last sentence. The trio includes a talented 8-bit animator, so prepare to spend the next hour in dreamland on YouTube. Just a couple of quick examples:

Muchas gracias to “Pants” in comments for bringing this to our attention, and, best of all, noting that you can get their albums outside Japan, along with plenty of other gems, at:

Records of the Damned