The social bookmark icons included in this set among others are: Blogger, Delicious, DesignFloat, Digg, Facebook, Flickr, Google, a heart icon that will work for anything (such as bookmark), MySpace, Reddit, an RSS icon, StumbleUpon, Technorati, Twitter, WordPress, Yahoo! and YouTube.
Update: Now 27 Icons instead of original 17 icons. The new icons added in August 2009 were AIM, Bebo, eBay, Hi5, Last.fm, LinkedIn, Windows Live, Ning, Orkut and Yahoo Messenger.
Free Social Bookmark Icons for bloggers - Social Media Icons Pack - 27 free circular icons suitable for general use
Social Bookmark Icon Set - Social Media Icons Pack
Number of Bookmarking Icons in Icon Set
27 icons in set featuring popular online social networks and Web 2.0 sites
32x32px, 64x64px and 128x128px
Suitable for Wordpress, Blogger, Drupal, Typepad, Joomla and other website applications
Free to use on personal or commercial blogs
Free Social Bookmark Icon Sets