The shots on this thread continue to amaze me.... I have nothing comparable, but I did recently get the new 100-400 and have been trying to get a few bird pictures lately. Specifically, a couple hawks (?) have taken up residence in the area around my house. I've sort of made it my goal to get a good picture of one of these in flight, but it is tough! Here is one of the better one's I've gotten so far:

4N9A9523 by Stephen, on Flickr

By the way, I think this is some sort of hawk, but I'm not sure what type. Any help with ID would be appreciated!