One of my favorite extra-special accoutrements for my knitting experience is my ball winder and swift. Wait, I guess that's two things. Anyway, if you're looking for something really nice to get a knitter in your life, or something to add to your knitty wish list, this is the thing. Or things.
I think of them as one thing because you pretty much always use them together. You could just have a yarn swift, I suppose, and wind the yarn off by hand, but it's ever so much easier to use a ball winder and swift together to wind an hank of yarn into a ball.
There are lots of reasons to want a winder and swift, but I really love them for the ritual, the building of anticipation that a new project is going to start soon. (If you already have a winder and swift, share why you love yours here.)
And if you really want to gild the lily, ask for an electric ball winder. It's faster and less work than the hand crank kind, but a little less romantic, too. Your choice.