I work primarily with SharePoint and in SharePoint you end up with plenty of very long URL's that you need to send to other users via email. Given that, I felt it would be nice to have a simple way of creating short URL's that link back to what is in SharePoint - document libraries and lists to be specific. This is something that I implemented via a custom action on the ECB menu.
In conjunction with that, I decided to create a very simple web site that provides a similar service to other sites out there, but to offer up the source code for the core capabilities - not including the SharePoint components.
One of the goals was to provide database independance - and ultimately, provide a configuration driven ability to replace the persistence for the back-end DB needs. This version that's supplied here supports both SQL Server 2005/2008 and MySql 5.x.
For more background information, see my blog post describing the implementation.