Default Audio Changer is a program that can change the default audio device on a Vista & Windows 7 OS-es. It is especially useful if you're like me and have a sound card with speakers attached and a USB headset/headphones.
It is made for lazy people, so if you're not lazy, you can continue to use the control panel application (mmsys.cpl).
Easy to configure, minimalistic design, fits well in the tray, works flawlessly. All the competing utilities can go and... I don't know, do something else.