San Juan worm or Stonefly nymph would be my top two choices if i didnt have any "carp flies" in my box.
Anything buggy really. Here, have a look at a page on the blog, Fly Carpin.
Lots of really good carp flies from a recent fly swap on the Carp Pro forums. There are a couple flies in that mix that are made by members of this forum.
Fly-Carpin: 2012 Carp Fly Swap
Hopefully McTage doesnt mind the link...