I have an ATI Radeon Xpress 200 (integrated, but hoping to upgrade it), and I’ve found ATI Tray Tools very useful. When I upgraded my drivers, it messed up the brightness/contrast/gamma sliders so it was all in one “brightness” slider, which I wasn’t too happy about. Then I found ATI Tray Tools which lets me adjust them seperately!
Also, on games, it provided a number in the corner — recently figured out it was the framerate. I personally stay away from the overclocking settings, but there’s plenty of things in there I haven’t touched yet.