Penultim.it is a URL-shortening service that can't let go of the past. Instead of providing a shortened link for a user's submission, it defies expectations to help us find something new. When a user submits a link to Penultim.it, they are given back a shortened link to what the previous user submitted. By doing so, Penultim.it raises awareness of the potential dangers we may encounter when using URL shorteners. In addition, it encourages the idea of 'accidental information encountering', in which we come across unexpected content outside of the closing grasps of our social networks.
It was built as an extension of the YOURLS library. YOURLS (Your Own URL Shortener) is a loose set of PHP scripts that allow developers to run their own URL shortening services. With some knowledge of PHP, you can make it private or public, pick custom keyword URLs, and it even comes with its own API. It's a fantastic, lightweight and effective solution which allows for a wide range of possibilities.

URL shorteners are a relatively new technology but have grown increasingly popular with the mainstream ascension of Twitter in the social media landscape. Their primary function is a machine-oriented concern: limiting the length of a string based on an essentially arbitrary service limit (140). The increasing number of such services has not led to much innovation beyond the primary functionality. Statistical metrics and bookmarking functionality aside, URL-shortening services as a social interaction are only beginning to be explored, with Stumble Upon's toolbar and Hoot Suite's similar offering.
Penultim.it subverts the intended interaction of URL shorteners in order to encourage an increasingly overlooked form of data consumpion: accidental information encountering. While ShadyURL subverts the shortened URL provided for a humorous effect, Penultim.it is inspired by the interaction encouraged by the Kashiwa Mystery Cafe and the now-defunct Mystery Google. Both worked upon the same principle: allow the user to input a selection (be it food or search query), and receive back the selection of another user (someone else's meal or search result). Penultim.it takes advantage of the obfuscation inherent to URL-shortening services to accomplish its goal.

Amongst recent social media technologies, URL shorteners perhaps best reflect the dangers inherent in adopting a machine-oriented view of technology. Users cede control of links that are somewhat-human-legible with the expected return of machine-readable, encrypted links. Users are asked to place their faith in a machine, but the history of these services has not shown they deserve it. Their encrypted nature mean that shortened URLs are prime targets for malware addresses amongst other spamming measures. In addition, their short history has shown there is no guarantee these services can sustain extended use. Tr.im recently announced it would have to shut down it's services, after Twitter declared bit.ly to be it's official link shortener. With Twitter's backing, Bit.ly went on to become market leader, but less than a year later it's own position is tenuous with Twitter's announcement they would be launching their own service.