Diigo, finally, has some of these new ideas. They allow you to highlight text on a page, and share those highlights. You can then view those highlights the next time you see the page, and they are included in your bookmark list. You can also “extract” the highlights: check some items in your list, select “Extract highlights”, and a web page is displayed with a list of the selected items and their highlights. You can also add sticky notes to the highlights, and share them. That way, everyone can see your notes, and even respond to them.
There’s also the Diigo toolbar, which has some good extended features. Annotations are for example always displayed, and not only after you clicked the bookmarklet. You can also search via the toolbar, bookmark quick (without entering tags), bookmark to other services simultaneously, and blog about a page. When bookmarking, the toolbar also allows you to immediately add a new comment about the page, something the bookmarklet doesn’t allow. What both the toolbar and the bookmarklet allow, is forwarding the page via mail to a friend, with a customized message and the highlights on the page. I don’t really like toolbars, so I won’t keep this one installed (or I’ll at least hide it), but I think the toolbar can be very helpful for some people.