While I have used (mainly out of curiosity) well done utilities like OnyX and a couple others, I strongly recommend against using this kind of utility while fully booted. The real work just can't be done properly without risk. Permissions fixing is fine but for everything else, I'd heartily recommend another free utility called AppleJack. It's also free and works at the system/super-user boot and ''just plain works.'' Every Mac geek I know swears by it--especially before doing a major OS upgrade (like 10.5.5 to 10.5.6). Personally I have never ever had any of the well documented ''catastrophes'' of major OS upgrades, and I attribute it all to AppleJack and a rigorous upgrade scenario.

I am in no way affiliated with the people/group who give us AppleJack--just to make that clear.

It does all the work simply and with or without any interaction or risk of ''doing something wrong.'' You can run it in ''auto'' mode or not. You can run a ''deep clean'' or just a basic maintainence scenario. It also works on both the PowerPC (G4) through the latest Intel boxes.

Again, nothing wrong with any free and helpful utilities. We have to keep inspiring these gals and guys to continue their hard work for such a ''great price.''

As for OnyX in particular and the risk of a user ''overdoing'' things, I suggest less rather than more customizing in the way of checkboxes and so on. Perhaps a simple drop-down with fewer ''safe'' choices that lessen the risk of tempting any disasters. Simplicity is best.