I have a new MacBook, and love using its keyboard. However, I fear that the area where I rest my palms will get dirty over time - a shame, considering how great the unibody aluminum looks!

The industry standard of protection solutions seems to be the Moshi PalmGuard. What I don't like about it is that it's permanent: you stick it onto the machine. It promises to come off without a trace, but I would still prefer a solution that I can put in place, and remove whenever I want.
Are there any solutions for this? I do not use the trackpad, so it could well cover the entire front area for my purposes.
