my 'friend' lost his cd-key for half life also, he went to wal-mart and opened a box and wrote down a cd key, then he took his car keys and scratched out the cd key and put it in the box. he went home ...
It's odd because this runs in to a whole new issue in terms of online ethics - that CD keys are not altogether a secure way of ensuring proper gameplay online (in that people who paid for the game ...