A URL Shrinker is a webapp that allows you to input a very large URL and it'll output a short URL with which you can distribute to your friends and family.  The advantage to shrinking a URL is that you can verbally relay it to people or email it and not worry about your mail client word wrapping the URL (and thus breaking it).

I wrote my original URL Shrinker in PHP and decided to port it to ASP.Net since its such a nifty little app. 

Here's the article on how to implement your own:  http://blogs.msdn.com/kgrey/articles/URLShrinker.aspx