TweakUI

Microsoft has a somewhat famous PowerToy for Windows XP called TweakUI. It allows users to play with several user interface settings that are built into XP but aren't easily accessible out of the box. It's available at

http://www.microsoft.com/windowsxp/Downloads/powertoys/Xppowertoys.mspx

Turns out there's an equivalent tool for Windows Vista and 7 — though not an official Microsoft product — available at

http://www.thewindowsclub.com/ultimate-windows-tweaker-v2-a-tweak-ui-for-windows-7-vista#more-1957