If you're at all interested in fiber arts involving yarn at all, you simply must buy have a yarn ball winder. This is the one I have and it's great... I like to buy old tacky sweaters at the salvation army and take them apart for the yarn. This gadgam-gig pulls the yarn from the sweater/scarf and winds it into a ball, without knots!

It's ready at this point to be reused and made into something else beautiful, It goes easily from a know free ball into whatever format you'd like to have your yarn in (if you're going to dye it etc.)