I’d love to see a “really social bookmarking”. Delicious has lots of bookmarks, and shows which bookmarks are popular, but it’s hard to figure out who people are because most people use pseudonyms. Magnolia (RIP) had much more social presence but was small. Twitter is timely and social but amnesic. Friendfeed has people and multiple services, but you can’t navigate it by content type (links) and topic (tags).
I’d love to see bookmarks through a multi-service friend of a friend network, browsable by topic, prioritized by number of links. That would be a great way to find classic information and good curators.