http://f.cl.ly/items/0H153y1K0R2S0c3w1j0P/Screen%20shot%202011-08-13%20at%205.28.28%20PM.png I'm trying to find out why FireFox 4 doesn't have it, because I used it a lot with FF3. So I need the name to search for it properly.
Most people just call it the tool bar "pill", I think it's technically called the "toggle toolbar button". https://addons.mozilla.org/en-US/firefox/addon/restore-toolbar-control-pill-b/ The button no longer exists in Lion so apps will probably continue to remove it as they're updated.
