Ever since mice lost their balls Iíve used paper from my laser printer. It protects my desk from wear, is so thin that it doesnít make my wrist bend any further upward (as the old foam ones did), and I use the far edge/corners to jot down notes related to the current project or when on the phone, etc.
When the paper gets wrinkled and grotty I save any needed notes and get a fresh sheet. I donít do this often (not on first signs of wear) so Iím not wasting a ton of paper, especially when you consider that Iím getting dual use as a scratch pad. (I often let them get pretty worn out, but in realty theyíre no more unhygienic than most peopleís mouse pads even if the paper looks bad toward the end.)