WapURL.co.uk has launched an API to create short URLs on the fly.  If you’re like me and send emails and SMS messages with long links then this API will help, basically it saves you having to send massive links.  Click here to see how to use the API. 

From the site:

Overview

To perform an action using the WapURL API, you need to send a request to our URL specifying some arguments, and you will receive a formatted XML response. Send URL requests to: http://wapURL.co.uk/api/

• The REQUIRED parameter URLToConvert is used to specify the URL you wish to shorten
• The optional parameter urlEncoded is used to specify a if you have encoded the URL that you are passing.
• The optional parameter charset is used to specify a character set that you have encoded your URL in.
• The optional parameter requiredKey is used to specify a key that you require to use - must be 7 characters long, if this is already taken will generate another key for you.
  Note: If the url has already been converted you will receive that key back.
• The optional parameter required is used to specify if the required key has been encoded, this will use the charset to decode.

What’s really cool about the API is that they have also created a firefox plugin that will allow you to right click on a webpage that you’re browsing and send that website URL to there API.  It will then show you the short URL that it has created which can be copied and used.