Here are my top 5 amazing facts:
1. Crows display remarkable teamwork. You may have seen them mobbing a hawk to make it go away. They've also been seen to steal from other animals in pairs -- with one pulling a seagull's tail, say, while the other crow grabbing the tasty mollusk the seagull drops. And they have been seen to come to each other's aid, helping an injured crow walk to shelter.
2. Did you ever learn in elementary school that one of the things that separates humans from the animals is that humans use tools? Well, crows use tools. For example, this one figured out how to bend a wire into a hook to retrieve food.
3. Crows recognize faces, remember the behavior of the people with those faces, and pass on knowledge of the faces to other crows. If a person wearing a certain mask does something to threaten or annoy a crow, anyone wearing that mask in the future will be scolded and harrassed by crows in the area.
4. Crows are very persistent. One Seattle resident spent a day shooing crows away from a robin's nest in his yard (crows steal and eat eggs). For a year, scolding crows followed the man to the bus stop every workday, sometimes dive-bombing and hitting him in the head. When he moved to a new house 20 blocks away, he left at three in the morning to be sure the crows were asleep and wouldn't start pestering him at his new location.
5. A raven saying "Nevermore" is actually possible. Crows and ravens have been known to learn short words and phrases. Some even appear to understand the context of human language: one responded "what?" when its owner called it by name; one would say "Hello, Bob" only to its owner Bob; one would reply to "that's for you" with "that's for me."
There's much more detail on how crows do this, and possible reasons why, in Gifts of the Crow. Have you observed any cool crow behavior? We'd love to hear about it.