When I make seitan, I roll it in tin foil and twist the ends (like a sausage) and bake it at 325 for about 90 minutes (instead of boiling or steaming) -- it stays very dense (not spongy at all) because it has no where to expand in the tin foil. Then, you can slice for sandwiches, or dice it for mock *chicken* salad, or stir fry or whatever.
HTH
ETA: oh, soulbliss already posted the link to how I do it!! (from post punk kitchen) whoops!
Anyway, it turns out great!