I have noticed there is a lack of options in the Members List to arrange your users by different method. Like "Date Joined, Last Visited, Post Count (Low or High)" e.t.c. Plus one or two other ways of arranging members there which can prove useful at times, especially "Last Visited". I know some info gets displayed in the small image blocks located in the side panel, but it's very limited and you can't arrange the "whole" members list with it to cover everyone.
Marking forums as read fast by being able to click any of the "Forum Status Icons" on the homepage itself. I find that feature in MyBB very good, it's a very fast way to mark any forum read directly from viewing the forum homepage itself.