A key to cycle between available selections at the current cursor position—e.g. if I have a text object over a bunch of tree objects and I foolishly forgot to put them on separate layers, it can be difficult-to-impossible to select the text object without first moving away some trees. The object list is a great workaround, but being able to press a key to cycle through whatever selections are available is a feature I would use ALL THE TIME (as long as it's a key I can easily access from my left hand).