Temporarily disable UAC in Vista without rebooting
Odds are the times you get most frustrated with the pop up warnings are when you're installing and testing new software on your computer, so it'd be nice to turn off UAC temporarily and turn it back on when you're done. But by default, that means rebooting your computer twice, once when you disable UAC, and again when you turn it back on.
TweakUAC is a nifty little freeware application that lets you quickly turn UAC on or off (which requires a reboot), or sets UAC to operate in quiet mode. What's quiet mode? It means that UAC is still running, but it won't display warnings if you're logged in as the administrator. Best of all, no reboot's required, so you can switch to quite mode while you're tweaking your software setup, and switch back to normal mode when you're done.
TweakUAC is an executable, meaning there's nothing to install. But if UAC is running normally on your PC, you will have to deal with a UAC prompt every time you run the program.