Short
During the #100DaysOfCode challenge I was not only keeping a log of my progress, but also tweeting about it. In those tweets I also typically included a link to the commit showing the code I had created that day. Because of the size length limitation of tweets, I did not want to waste characters on the link (which is typically pretty long when linking to a specific commit on GitHub) and therefore used URL shortener services like Bit.ly or TinyURL.
When I was trying to come up with a new project idea, I thought I could just replace the use of these external services and create my own URL shortener. And so I did. Short is certainly not as feature rich as some of the shortener services out there (e.g. no analytics) but it provides the basic functionality that I was looking for. I also included a public API endpoint that allowed me to make use of Short in my command line tool (Logtweet) to generate tweets based on my #100DaysOfCode log.