Kevin Kelley’s Cool Tools blog points out these terrific Write-on Poly Static Cling Sheets. The folks who suggested these seemed pretty enthusiastic:
Polysheet instant whiteboards are thick, static-laden sheets of plastic, like ultra-heavy garbage bags. Just unroll one, slap it on the wall, and instant whiteboard! Best of all, in the corporate world, at the end of the meeting, you can roll them up, take them back to your desk, and process them. After capturing the contents in your computer, wipe them off for next time!