I've found myself switching between the 1440x900 and 1920x1200 "effective resolution" setting depending on what I'm doing (need more space on screen, etc).

1. Is there a way to toggle between these two modes with a keyboard shortcut?
2. Can I invoke one mode with a keyboard shortcut?
3. Alternatively, can this be done via an AppleScript (and therefore bound to a keyboard shortcut)?