Links:
[1] http://pulse.veltsos.com/category/it/social-networks
[2] http://pulse.veltsos.com/category/it/twitter
[3] http://pulse.veltsos.com/category/it/visualization
[4] http://linux.philosweb.com/drupal/system/files/Twitter_veltsos_2.png
[5] http://www.tweeterbrowser.com/