To set the title of the page, modify the query part of the URL (the part at the end, beginning with a question mark) or the input field below. It will also update the URL, so there is a small delay to reduce spamming your browser history while typing.

Why? I really like the Firefox extension Tree Style Tab for organizing my tabs. It gets even better if I can group tabs under a tab whose title I can set myself, and a page like this was accomplishes that goal orders of magnitude more easily and quickly (cheaply.)