"Just a hint - you don't have to make a Reuben with the traditional Swiss cheese - I found that sliced Havarti from the local supermarket is actually an upgrade."
You don't have to be a godless heretical Communist America hater, either, but there you are...
I've always wanted to try Limburger on a Reuben...
I think that kick-in-the-balls pungency would work really well on a Reuben with is already chock full of strong, pungent flavors....