Instead of only being able to see activity log when in a case, seeing "last visited" or "last edits w/in 24 hours" etc would be helpful. Yes there is a drop down in the search that shows last 4-5 cases accessed, however seeing a timeline of all activity a user took in that day would be so helpful!
I believe you can do this in the activity feed from your dashboard by modifying filters. However, I also think it's permission dependent.
From the dashboard, if you have the proper permissions, you can filter by user, type of action, etc. I find it very useful.