Ask HN: What killer feature(s) are social bookmarking sites missing?
What features would you like to see included in Delcious, Stumble etc? Is there a big gap in social bookmarking that has not been plugged?
(Personally, I wouldn't try making yet another social bookmarking site. The only way I can see of competing with the existing players is to market it better so that you get users who've never heard of Digg/Reddit/SU/Delicious/etc. Hint: Facebook app, viral features. But I'm not sure how succesful at making money these sites are.)
* Tracking my most-searched-then-clicked-on links, and showing them in a "Personal Top 10" stack for quick viewing, which in turn would be its' own bookmark folder.
It is not so much surfing history, but more a question of how likely I am to want to go to a certain link when I visit my bookmarks.
I'm still waiting for someone to bring the pleasure of the Firefox address bar to a social site. I created a webapp that does this last summer (Quocial.com; I can send you an invite if you like, but be warned that I'm no longer maintaining the site), but the technical difficulties of full-text search are such that it really only makes sense for someone like Google or Microsoft/Yahoo to do this. Or, Twitter could start crawling links and letting you run full-text search over either your links or those of the folks you're following (though I'd rather not make each and every one of my links public).
In short, the social bookmarking game isn't over yet. I firmly believe that Delicious-style tagging will give way to full-text search. One of these days, someone's going to nail it.