Maybe I'm the last person on earth to get the memo on this, but I've had several horrible experiences in my life where I've picked up a permanent marker on my way over to the whiteboard, drawn all over the thing, and then realized what I was doing. Its usually possible to clean permanent marker off, but in the past is has entailed a LOT of work. Today a small bit of information that I was missing was dropping to my lap. Apparently if you draw over the permanent marker with a dry erase marker, you can then erase the marks! It works amazingly well.