Here's a great way to make use of all those left over short ends and half balls of wool. I'm usually not a fan of knitting blanket squares but these have more appeal and are so easy. The pattern is here Log Cabin Scrap Blanket Make sure you watch the video on the site that explains the process so well and shows how the strips are knitted on to make each square. I would endorse her three rules:
1. No single colour should dominate a square
2. No single square should be dominated by mostly dark or mostly light colours
3. Keep really uncomplementary colours from touching each other.
and also add
4. Repeat at least one colour if possible in each square to create a unified design.