I click my tank timers (2+ minute CDs) and Medpacs and Relics. Also various AOE attacks with DPS.
I do this knowing that keybinding is way more effective, but once I get outside of the 1-5, r, t, f keys, things start to get messy when it comes to remembering what is what, so I just use it for stuff I shouldn't have to do often.
FYI, using the mouse for shifting the camera, strafing, and kiting is far superior to any other method (of which I am unaware).