You have so many features using this URL shortener. You also don't need to register to use all feature. Best is to configure your shurt URL with a passwort or set a limit how often it can be called. So you have a very good protection to it.
shorturl.is - Make long url's short. Statistics included!
YOURLS - YOURLS is a website that contains all the tools you need to create and launch your very own URL shortener. URL shorteners like bitly or TinyURL are fine for public use, but they offer limited options in terms of URL customization.
Capsulink - Capsulink is a URL shortener that gives you the key tools you need to optimize your content and marketing strategies.
Lstu - A nice and open source url shortener. You can use it as service or install it on your own server.
ShrtFly - ShrtFly is one of the best URL shorteners, They offer Higher Payout Rates on Norway and United States Country.
Anonymous URL Shortener - Anonymous URL Shortener, Referer, Anonymizer, Redirection service.