It had obviously been used in the gym, since it had instructions to add your name to the wait list for machines, which had been on the board for enough years that it couldn't be erased. I tried the usual tricks; water, white board cleaner, writing over it with new pens, and only the pens worked, but would have taken forever to get it all off. I finally remembered that I have a little bottle of Simple Green in my tool box, and that did the trick (with a 10 minute soak). There are a few scratches on the surface, but for free, its still a good deal.
10 points if you can figure out what circuit that is! Note: It runs on 9-12 volts DC.