Triggered short duration flash.
Hummingbirds are not a problem. It is easy to get a flash that makes daylight look light night (There is an example in the Speedilite book Bob reviewed), so absolute darkness is not required.
Beyond that, as this (http://en.wikipedia.org/wiki/Hummingbird
) states, the wings beat up to 90 times a second. So a 1/90th shutter would capture a full beat, a 1/900 second shutter would capture 1/10th of a beat and a 1/5000 shutter would capture about 2% of a beat.
Sunny F/16 says that in full sunlight, your shutter speed is 1/ISO
So, we start at ISO 800, which says that we use a 1/1000 shutter.
From there it is only 2 stops to 1/4000 which is f/8.
It should be easy to stop a hummingbirds wings in full daylight.