Community has some pretty awesome musical moments, namely from Those Two Guys Abed and Troy. Their duet of Somewhere Out There while trying to coax a mouse or rat which gets an awesome Celtic kick to it. The music also perfectly weaves together the three scenes.
In general, the decision to score the zombie-movie episode (2.06) entirely to ABBA songs. It lands somewhere between this and Crazy Awesome.
The show's usual theme song is pretty good, but it becomes truly epic as a fantasy-esque piece at the beginning of "Advanced Dungeons and Dragons".