Laptop skin that is a rocketbook erasable page
I was chatting on a forum today, and we were looking for quick ways to keep quick notes and other todo things. If I could write these on the back of the laptop screen (or the tablet-back) it would make a big difference.
Upside for you is that i'd probably need to replace it from time to time. Ideally the edges could be a little more protective, so it doubles as the normal reason you get a laptop skin.