Kirk, do you have the 500E factory service handbook? It is separate from the owner's manual, and lists all procedures, and has detachable coupons to show what was done. It ought to be in the zippered black leather manual case.
I've got a sixty-K coming up myself and I'll post what the book recommends. I believe there's a transmission service and a cooling system flush and a couple of smaller items; it's certainly more than just an oil change and a wash.