How smart are sheep? - An article about specific cognitive tests done on sheep and their surprising results.
The answer is smarter than most folks give them credit for - a summary of all sorts of interesting information about sheep behaviour.
In the first article up there, their intelligence is compared with that of monkeys and the sheep come out favourably. I keep saying, the number of times I've seen sheep get the better of people and people still think they're dumb - What does that say about people?