Steps for IE
1. Open up Regedit (Start>Run>Regedit).
2. Navigate to this string: HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
3. Create a new string value (Right-click "Main" key folder, select New>String Value).
4. Rename the value "Window Title" without the quotes (Right-click value, choose Rename).
5. Right-click "Window Title" and choose Modify. In the value data section, type your title of choice. Mine says "Elect Sarah in 2004!"
6. Now, launch a new instance of IE and marvel at your clever changes!
Steps for Firefox 0.9 and up
Wouldn't you know it... there aren't really any complicated steps to do this. Just download an extension called Titlebar Tweaks and you'll be good to go.
Sarah Lane hacking tip