Our absolute favourite couch quilt (the one the kids all fight over) is backed with a faux fur throw! lol
It feels awesome, and is so warm and snuggly. It provided a few challenges quilting it, with the long fur getting stuck under the quilting stitches. But over time they've come back out and now you can't see any quilting from the back.
You'd be surprised what you can use for backing with a bit of imagination. ;-)