This is my best shot so far. Taken at Rondeau Provincial Park during 2008 spring migration, the picture shows the fight between a Northern Flicker and a Red-headed woodpecker over a nest hole. The fight ended with the Red-headed woodpecker pair being forcefully evicted from their home by the invading Flickers. Within 2 days, the Red-headed woodpeckers rebuilt their home about 100 feet from their original location.
What you see in this picture is the Flicker holding the Red-headed by its tongue while spiraling down towards the ground. Talk about unique bird behavior.
This picture has since been published by National Geographic in the 2009 January edition. You can see it here:
or here (if you care to have this shot set as wallpaper)