I'd like to see an option to click a checkbox on a list to have it function like a wishlist and remove games once I've purchased them.
I've got a catchall list called 'misc' that I add ALL games too that I haven't really looked at but found kind of interesting, usually games I just downloaded the free content for to look at later. It's actually gotten kind of MASSIVE, since I add anything to it that's not in my wishlist or purchased games, so an option to automate removing things would be very convenient.