Whether you want to spice up your key ring or maybe cut down on the jingling, the Creative Key Cozy is what you're looking for. The pattern is knit in the round using the magic loop. It's easy to learn how to knit this pattern and you can use leftover yarn too.
DIY Colorful Knit Blanket. No pattern, no pressure. Just use up your yarn and knit scarves using the garter stitch (knit every row) and seam them together. A good post on knitting what you love, and more directions at Completely Cauchy here.