Hooray for Web 2.0 products! They seem like a great way to engage students and make learning interactive.
Xtranormal.com seems like a tool I will use often in my theater classes. For free, students can make movies wherein two animated characters interact with one another. This will be a great way to talk about different cultures in social studies or work on dialogue construction in drama.
Prezi is like Powerpoint 2.0. More fun, more zoomy, more full of life. A little more complicated though, so I gotta be careful about overstimulation in the classroom with Prezi. Used carefully, it can be awesome.