I think toolbars bring more usability, and every web site like Diigo and WebNotes have also bookmarklet equivalents (may not have all of the functionality, but useful). There is some part of the functionality I have told it should be on Diigo, like lists, tags, and other annotations and you can configure the toolbar for extra filters, but I think this functionality should be more complete if it has the things I mentioned. PDF support and annotation will be great too.
Diigo should also consider PDF support & annotation, more and more services offer that feature.
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