You can tell how fast a hummingbird beats its wings by measuring the pitch of the humming noise. read more
The smallest and allegedly fastest hummingbird is the bee hummingbird, which beats at about 80 beats/sec. There are many reports on the internet of the ruby-throated hummingbird beating its wings at 200 beats per minute. This seems to me to be impossible and I cannot find a reliable reference for this. read more