I love wooden furniture but sometimes I do worry about knocking and damaging it - or in the case of this sofa, the damage that a the back was threatening to the freshly-painted wall. After just a few days we were starting to see a slight mark on the wall, just from sitting down.
It turns out that a length of cheap pipe insulation is perfect for protecting walls and furniture from one another. It holds itself in place, takes seconds to fit, and you can't even see it from the front.
You just need to find a piece of insulator that's designed for a pipe about the same size as than the part of the furniture you want to protect, or slightly smaller (because this stuff is quite stretchy and you want a snug fit so it doesn't fall off). If the insulation is a solid tube, as mine was, you also need to cut a straight line along the length so you can open it out.