[Handycam]

Well, in FF, the file menu says "Close" (cmd-W) for a single tab. Open up another tab and now you have "Close Tab" (cmd-W) and "Close Window" (shift-command-W). This, I like.

This way, if I have a Cocoa gesture (or, in FF's case, a mouse gesture) linked explicitly to the "close tab" command, if the command is grayed out, my gesture does nothing and I don't inadvertently close the last tab.