I just ran across a place where you can get patterns to knit covers for your plastic chairs. The Knitted Chairs started out as a final-year project for her degree in product design at Middlesex University in London, and includes free patterns. Be sure to check out the gallery. You'll want to use really big yarn - maybe ply together a few strands of dead-in-the-stash yarns on your spinning wheel, and dress up your plastic chairs! (and clear your stash of guilt...)
I wanna see pictures if you do one!