Instapaper. I know that's kind of a cop-out but incidentally it (and Google) have killed my use of bookmarks apart from a relatively svelte bookmarks bar. Instapaper is my reading queue, Google is my long-term memory. Bookmarks are more like shortcuts for me now.
The nice thing is that I can "bookmark" any link from any browser that I use, as well as twitter and RSS. And I have them instantly on my iPad, phone, notebook, or any machine with a browser without installing any software or extensions.