Custom / New Vendor Withdrawl Options

Would it be possible to have new withdraw options added for the Marketplace? I think setting up a custom string that would let users name the service and then request vendors provide an username/address option would be ideal for a range of new payment services.

If a custom string would be an issue is it possible to have an option for Bitcoin to be added? This should allow the vendor to provide a receiving address where they would like their payments sent.