The Best Illusion of the Year Contest is one of my favourite parts of the annual Vision Sciences Society meeting, and the webpage gives you a good taste of these brand new and often stunning illusions.
Another wonderful source for visual illusions is this page by Michael Bach, which has 104 of them!
You can help vision science right now! TestMyBrain.org lets you contribute data to real experiments — including ones that test whether you might have prosopagnosia, aka face blindness.
A nice blog post about how to interpret error bars, from Cognitive Daily.