Marshall - 7:25 pm on Feb 11, 2012 (gmt 0)
John, hate to say, but it is rather subjective. When I get referrals from a customer and it is a large job, i.e. a new site or major overhaul, I usually give them one year's free web hosting, assuming I host their site. Otherwise, I generally give $50-$150, again depending on the job. A third option I have done is send them a gift card to a chain restaurant which is safe to assume is in their area: Olive Garden, TGI Friday's, etc.