web services: URL shorteners and Clean URL; URL design.

A shortener:
Paste your long URL and you get a new short URL.

URL shortening is a technique in which a Uniform Resource Locator (URL) may be made shorter in length and still direct to the required page. This is achieved by using an HTTP Redirect on a domain name that is short, which links to the web page that has a long URL.

http://goo.gl/
(this allows other services linked with your google account (your feed; analytics...))

http://en.wikipedia.org/wiki/URL_shortening

It's different of http://en.wikipedia.org/wiki/Clean_URL

http://warpspire.com/posts/url-design/