This from a letter sent to Seth Godin’s Blog:

Now here’s the best bit… The only way you could become a client of
Paddis was someone had to REFER you. IN fact the referral bit was a
condition of doing business with him. Before he would work on you he’d
say… I’m going to give you the best dental treatment and in return I
have one condition that you must meet… you have to refer at least 3
people to my business.

Paddi realised that getting A customers to refer their friends would
simply generate more A customers… people have friends that tend to be
like themselves… good payers etc etc.

The beautiful thing is….Paddi’s a Dentist! There is another wonderful example of marketing using the Free Prize Inside concept in the most recent post at Seth’s Blog.