How cute would it be to wrap up the gift using a bit of the yarn you used to knit it? Like a tiny preview of what's inside. Here's a couple ideas for ya:
Similar idea, but attach a few tassels and it's instant-fancy!
Make a tiny pom pom and wrap a little yarn around a plain box and you are good to go.
Keep it simple with some pretty colored paper and a big chunky yarn bow!
If you want to get really fancy, weave a little yarn in two colors around a box, how neat and clean does that look??