I think that a very usefull feature would be to put a kind of a mark of the clip thumbnail in the Media pool to indicate that the clip has been used on the timeline.
This information is available in the "Detailed view" in UseCount, but would be great to have it also in thumbnail view.
Yes, you're right, but I think that most of the users are working from the "Thumbnail view". Therefore it would be great to have this info also repeated there.