Twitter and Facebook users are familiar with URL shorteners, the web tools that turn long and unwieldy links into short, shareable ones. Bristol-based shrtn is adding to that concept by helping social media users earn some extra cash while sharing product links. Like other shorteners, shrtn has a simple interface that lets users enter long URLs, which are then shortened to something like http://shrtn.co/hb (linking, in this case, to Steven Johnson’s Where Good Ideas Come From). The big difference with other services is that shrtn has signed up with over a hundred online merchants, and adds affiliate identifiers to their URLs. Ever time an item is purchased through a registered user’s shortened link, shrtn receives a commission and passes part of that on to the user. So if someone short-links to their favourite perfume on Beauty.com, and one of their friends follows that link and buys from Beauty.com, the user receives a cut of the affiliate earnings (shrtn pays out 70–80% of the total commission). Users receive their earnings through PayPal, or can choose to donate them to charity, in which case shrtn adds an additional 20% on top. By simplifying affiliate marketing for ordinary consumers and keeping the experience unobtrusive for those who click on links (it doesn’t add pop-ups or insert elements into the user’s browser) shrtn seems like a win-win for all involved.