IdeaPaint, but for any surface:

CLEAR can be applied over any type and any color of interior paint to achieve a dry erase think space that seamlessly blends with any decor. It is also certified low-emission, virtually odorless (insert happy dance here). This is one of those companies who make innovative products with a conscience (insert sigh of contentment here). To add to this they are donating $25 for each kit sold to charity: water a non-profit organization bringing clean, safe drinking water to people in developing nations.

Available at ideapaint.com.