Windows only: When it comes to getting deep into a Windows system and tweaking the stuff you can't get to from the Control Panel, the free tools provided by Nirsoft and Sysinternals are hard to beat. Windows System Control Centre is a free, no-install app that provides a convenient front-end for running every app released by those groups. The app requires that you keep each group of utilities in the same directory, but the majority of them are portable and USB-friendly. System Control Centre requires that you download the apps in question, but it also links to a few standard high-level Windows tools for all-in-one fix-it work. System Control Centre is a free download for Windows systems only. Update: austin316gb points out two links to download all the Sysinternals and Nirsoft apps in short order.