I find this a great idea: knit a soap sock that felts using it, similar to the felted soap.
But it goes a little further, because the author says in the comments that the soap sock becomes in time a smaller felted bag where you can put soap rests into. She uses them as scented sachets for her clothes drawers.
Links:
Tutorial: Soap Socks
Here at unikatissima:
Felting Soap