Welcome to our forum.
It always amazes me, Steve will dissapear for a few days and then WHAM! Come in with an article sized post full of profound and usefull info... What a guy!
My only suggestion is to have specific criteria. You don't want customers coming in 3 months down the road and saying that they referred someone but didn't get anything for it. I made up a form that had to be filled out at the time of the sale if there was a referral. A copy was kept in the file after the gift was issued. If it wasn't mentioned at the time of the sale, the jacket promotion wasn't allowed. Keep in mind that we asked EVERYONE how they heard of our store and if they were referred.