Open source software choices and suggestions:
yourls
If you like to post to Twitter and need to shorten your url links, this is a good package. Unlike using the “regular” packages that often are blackballed by security servers, this is a small install that works on any LAMP server, such as BlueHost (where mine is housed). It lets you create your short url for Twitter privately, with total control, and it works like a charm. It even gives you data on your clicks from your shortened url. You have complete control over the management of the shortened urls and can create them or delete them at will.
Download a copy at yourls.org, where you will also find all the documentation and configuration information you need to get it going.