Diigo is an online bookmarking site that makes it easy to organize bookmarks and find new resources.
These directions show how to add the Evernote bookmarklet; however the same process works for installing the Diigo bookmarkelt. The necessary code is below:
javascript:(function()%7Bs=document.createElement(%22script%22);s.type=%22text/javascript%22;s.src=%22http://www.diigo.com/javascripts/webtoolbar/diigolet_b_h_b.js%22;document.body.appendChild(s);%7D)();