I recently took a couple out to dinner for a referral and also included the referral party, it was nice and I got to see the couple whom I sold a house to.  Most times they get a gift card. I always send something in appreciation whether or not the referral uses my services (99.9%) of them do utilize my services. I've never gotten a referral on someone who was not able to purchase or sell, ever. No dead referrals here.