J.,
the only thing I could think of too, is dry erase markers.....what about the crayola washable markers? also, didn't crayola come out with some special kind of wash-off crayon....it's not like a regular crayon that is wax and covered with paper....i'm not really sure?!?!?
Try calling Michael's store or AC Moore store or even one of those teacher type stores....we have one here in Raleigh called "Teach Me".....it is a great resource for parents!
Good Luck,
Pam
ps...I was also thinking that I wish I had a creative friend like you here in Raleigh to help me with this kind of stuff! You sound great at thinking of fun kid things...I'm not creative at all!!!!