Pinboard.in is a social bookmarking service similar to Yahoo’s Del.icio.us. The major difference: Pinboard is not free.
They charge a one-time fee to join that is calculated based on the number of users in the system. This encourages a customer that’s on the fence to sign up now or risk paying more later. The price goes up $0.001 for every new user that joins ($5.94 at the time of this post). Genius!!!
This income stream allows the company to stand above other services in terms of customer support and reliability. If you have a question/problem, you’ll get an answer within minutes and you don’t have to worry about the company closing shop and taking your links with them.
Did I mention I really like the way they drive registrations and grow their bottom line? Kudos.