We often have promotional items/premiums we use as an enticement for joining or upgrading and would like to have the option of the member entering a code that will tell us what promotion they are replying to so that we know what gift to send/provide if they are doing this online or if we are entering the gift in back office.
The ability to enter a promo code for something other than discount or extension would also help us identify which appeal a webform customer is responding to.