Fast140 helps you test as well as improve your typing speed.

You can login using twitter oAuth. You would be given around 140 characters to type. Once you are done typing, your speed would be calculated instantly and added to your score sheet.

Based on your typing speed you are assigned a rank. The app even tells you the percentage of people you are ahead of with respect to typing speed.

Note: When you login to this application for the first time, the site would make you automatically follow it’s own twitter account @fast140 and also a promotional tweet describing the service would be pushed to your twitter timeline.