BoxBe is an interesting application in the information security arena. It leverages your existing social network to build an alternative anti-spam system.

“Rather than using blacklists and filters to stop unwanted messages reaching their in-boxes, why not charge advertisers for permission to send promotional messages? That is the philosophy behind Boxbe.” – The Economist

Rasba is a social network built around online shopping Retailers can set tup storefronts on Rasba and consumers who  buy from them can share their purchase with friends. If a recommendation leads to a sale, the person who made that recommendation gets a commission.

SaleShout is a Social Shopping Network Community which allows its users to posts links to Sales, deals and coupons.