Hippos can see under the water with excellent precision, but what is really fascinating about their eyes is the clear layer of membrane that protects them from debris found underwater. You can kind of see it in the picture.
Image: Ben Frantz Dale
Chameleons have some of the most unique eyes in the entire animal kingdom. They do not have an upper and lower eyelid, but instead just have a cone with a small opening just big enough for their pupils. Each cone can be separately rotated and the chameleon can actually look at two separate things in completely different directions at the same time. This visual advantage makes them exceptionally adept at hunting flying insects as they quickly buzz by.
Like most insects, butterflies have compound eyes, which are made of hundreds of microscopic, six-sided lenses that allow them to see in every direction simultaneously. While this type of vision prevents the bugs from seeing things in sharp focus, butterflies can see ultraviolet light, which is invisible to the human eye. This aspect of their vision helps to lead them to flowers filled with delicious nectar.