There’s this cello layering thing going around, which is neat because of the layering the player accomplishes with foot pedals and an Mac.
It’s worth noting, though, that people in rock and roll have been doing this for decades with devices gated up in all sorts of crazy configurations. It’s pretty common now to rock the house with a laptop running AudioMulch or some such, but going even further back the configurations of floor pedals musicians have wired up have always been a method for creating sonic layering, whether it’s an octave splitter or a loop and delay pedal.
This is a good friend of mine’s two person band, Giraffes? Giraffes!. If you are a fan of fusion influenced post-rock, watch it all the way through — I think they are one of the better post-rock bands out there. But if you want to see layering in a rock context, check out the bit starting at 4:30. I guarantee you you won’t be disappointed.
You can buy their album here, or download it for free off of any fine music torrent site (they encourage you to steal their music, seriously).