Tumblr

Tumblr is a microbloggin service that lets you effortlessly share anything. Post text, photos, quotes, links, music, and videos, from your browser, phone, desktop, email, or wherever you happen to be. You can customize everything, from colors, to your theme's HTML.

More info at http://www.tumblr.com/about

Icon: 
Code:
$links['tumblr'] = array( 'name' => 'Tumblr', 'description' => t('Share on Tumblr'), 'link' => 'http://www.tumblr.com/share/link?url=<encoded-url>&name=<encoded-title>&description=<encoded-teaser>', );
Example:
Add to ListOptions