Crows can remember human faces. If a crow encounters an unkind person, he will teach other crows how to identify that person. A grudge can be held for years.
Not your average bird brain, crows are known to use tools. Crows have been seen carrying cups of water, poking sticks into holes to look for food, and breaking pieces off a pine cone to drop on a predator climbing up to a nest.
Highly social creatures, crows will hold a funeral when a member of their murder dies. The funeral doubles as an investigation as the crows work to discover who killed their friend. Justice is then meted out as a mob.