Alex King's ShareThis wordpress plugin which allows visitors to share content via social bookmarking sites and e-mail the post to friends.
http://www.thunderguy.com/semicolon/2007/07/30/share-this-jquery-a-wordpress-plugin/
Widgets · WordPress Plugins
Get access to data on 90,688 websites that are ShareThis Wordpress Plugin Customers. We know of 29,148 live websites using ShareThis Wordpress Plugin and an additional 61,540 sites that used ShareThis Wordpress Plugin historically and 19,306 websites in the United States.
Get a list of 90,688 websites using ShareThis Wordpress Plugin which includes location information, hosting data, contact details, 29,148 currently live websites and an additional 22,903 domains that redirect to sites in this list. 61,540 sites that used this technology previously and 19,306 websites in the United States currently using ShareThis Wordpress Plugin.