Also if you continuously hit the "back" key until it gets to its last cached page, the browser will exit.
Takes a few more button presses, but will close it for you.
well, not quite... when the browser is loaded (with default google page) advanced task killer shows 106mb free, if i press back the browser disappears, however the amount of free memory remains the same. If i kill it with the mentioned app it goes up to 116mb.
Pressing home and back repeatedly does the same - just brings up the home screen...