I can't imagine why del.icio.us didn't work?!!?!?? I like diigo, but untill they give me all my links in a toolbar I still need del.icio.us...
At first glance, Diigo seems all over the map. The service offers bookmarking, highlighting of text within a page, commenting on a site for others to see, sending options, groups for networking and much more.
Diigo has been made as user friendly as possible by its developers