This post on microtiming in a riff from Metallica’s “Master of Puppets” is gloriously nerdy. If you understand this excerpt you’ll love it:

The problem is that on the album version of the track and in some live recordings, it doesn’t really feel like an even 5/8—the rhythm is consistently off enough that if you try to tap out really strict eighth notes, you end up not being with the band when you get through to the other side.

(via Jamie)