One set of browser add-ons in OS X are based on the Community Toolbar, and may be difficult to remove if the distributor does not include an uninstaller. Here is how to uninstall them. Topher Kessler ...
Two recent Apple KB articles of note: 106605: Mac OS X 10.1: Do Not Reinstall After Using the Mac OS X Update 10.1.1 states: "You should not reinstall Mac OS X 10.1 ...