Keyboard shortcuts are essential in being able to establish an effective workflow. Lot's of diigos functions could use shortcuts, but highlighting, bookmarking, as well as showing/hiding the toolbar and the sidebar appears to me to be some of the most crucial.
Bue Thastum commented
just found out that, except for showing/hiding the toolbar, the function is already there. A minor detail i that it feels a bit strange on a mac, not being able to use the command-key for shortcuts, but that's not that important.