DIY cushions for patio furniture. Super easy. I didn't have old cushions to cover so I used layers of cheap bed padding foam wrapped in batting. Look here for how to do boxed corners that are not covered well http://craftapple.wordpress.com/2007/09/01/sewing-tip-squarely-boxing-those-corners/
Upholstery for the lazy girl! When decorating, always keep in mind that no-one's going to see the bottom/back/inside. This is only one small step up from wrapping a loose piece of cloth over a cushion, but it does keep the cover tidy and in place. So: lay that piece of grey denim you're never going to make a skirt from, face up on the floor. Put the cushion more or less in the middle.