In reply to Monkeyrock:
I got some Mammut softshell trousers when I was in the alps last summer, and they've proven to be indestructable. I've cramponed myself, bashed into rocks, crawled over Chamonix granite in them and they've been great. On more than one occasion I've been bleeding prefusely in them from mashing myself against something, but the trousers have been undamaged.
Expensive though.
Tim