Thick wool is great to knit with, not only is it easy, but you can make something in no time at all. Annette from the blog Lebenslustiger shows you how you can knit cosy seat cushions. All you need is a little time, some wool, and your fingers.
Seat cover for dining chair. Clean, simple wrap around design that fits snugly around legs with velcro. This would be simple to make by altering this DIY: http://www.athomeonthebay.com/2012/03/dining-chair-drop-cloth-slipcovers.html