[URL]http://www.diigo.com[/URL]
Just found this today. Since del.icio.us is probably on the outs and Yahoo not doing much with it, and also the delicious toolbar not working on Firefox 4, I switched to this.
This does everything delicious does and also lets you save pages to your account, highlight text, save for later, save images etc. It seems pretty kick ass sofar. Also it allowed me to import all of my delicious bookmarks right from the start. Also there is an app for the iPhone, Android and iPad.
Check it out.
[video=youtube;0RvAkTuL02A]http://www.youtube.com/watch?v=0RvAkTuL02A[/video]