Want to find out how much time you spend on Twitter? Tweetwasters will just do that for you. Tweetwasters estimates that on average a user spends about 30 seconds on creating a Tweet. Multiply that by the number of Tweets you have produced and they provide you with the approximate number of days of your life you have spent on Twitter. The site provides a Hall of Fame of the Top 50 wasters on Twitter. Since this is a new service the Top 50 is changing often as more people come aware of the site. If you really want to promote how much time you waste on Twitter, just use the handy Wordpress plugin. You can see an example of the plugin in action on Sugarrae's blog.
Tip: The site provides an individual link to each profile that they calculate. While they nofollow the website link from your Twitter profile, they dofollow the Twitter profile link. So another easy way to build back links to your Twitter profile.