Short answer: no
Long: There's sort of a way but it's a PITA. Basically you'd have to start up an account, and file a claim with valve saying your key is in use. You'll email them a picture of your manual w/ the key (if you didn't buy retail you're SOL) and the key should be unlocked and linked to your new account. Of course this takes forever, isn't guaranteed, and your original account will probably be banned because they now have proof you weren't using your own cd key.