I have to say that I got the idea from the Plumo catalogue. They have crocheted covers for wire hangers which look very pretty. I used wooden ones which, believe it or not, I had to send away for. I bought them from a very useful site called Sew Essential. This is how you make them:
Collect together lots of odds and ends of wool, it doesn't matter too much if they're different thicknesses, I used double and 4 ply.
Chain 70 stitches and then work approx. sixteen rows of double crochet (you need enough to stretch around the hanger), changing colour on each row. The cover needs to be quite snug so that it doesn't droop of the ends.
When you've finished, poke the hook through the centre of the cover and stitch the cover in place from one end, along the bottom, to the other end.
To cover the hook, take two strands of wool and wind it from the bottom of the hook up to the top and back again, fastening off the ends at the bottom of the hook. You could also add a couple of pom-poms around the neck of the hook. I made some lovely little ones using a fork. There are instructions on this site with the great name Bored Blog Almighty!
You could knock one of these up in a night or two and I know I'd be pleased if you gave me one.