In the meantime I want to show you what I did to keep the balls of yarn from getting all tangled up. Here is my solution: I took a old shoe box and added internal dividers cut out of old cardboard. I then poked a hole in the lid of the box over each compartment.
I now have one ball of yarn in each compartment, with the loose end threaded through the hole. I keep the box on my lap while I crochet. This way the yarn doesn't tangle and the balls don't roll all over the floor.
It also make it easy to hide from my one-year-old, who thinks a ball of yarn is just the best toy ever!
PS: I know the box will look much better if I covered it in nice paper, etc, but I just couldn't be bothered. I'd much rather spend my time crocheting that decorating a box...