Sometimes I'm using my computer where there is no network connection; in those
areas, NetworkManager's icon spins ceaselessly, looking for a connection, and
sucking my battery via my wireless adaptor (and screen). It shouldn't time out
automatically, though, in case I come within range of an access point. It also
shouldn't simply stop animating and keep looking, as that would still use power
needlessly in case I knew I wouldn't be near an access point (I might be riding
in a car or train or space shuttle, inside a bank vault, or at my parents house
where they only have dialup).

The best idea I've had would be to have a menu item labelled "Disable" or
"Disable until I log out" or similar, so that if I plan on using the computer
with no network connection, NetworkManager (not just the applet thingy) can
bring down all the interfaces it's been monitoring and go to sleep. I should be
able to toggle back to re-enable NetworkManager, though, and it should probably
be toggled back automatically when I log out.