I have found out that the acer aspire one leather sleeve fits the A500 really nice and if you have a carry case and just want a little something for the tab this is a cheap way to have a nice sleeve. Don't know if this helps for anyone but like I said I just found out and couldn't be happier with it.
I grabbed the leather iPad portfolio case from Targus when I picked my unit up at BB yesterday. Really nice, very snug but since its leather I'm sure that it will stretch a bit as I start using it.