I think Prezi is a neat tool for students, because it's much more than just cutting and pasting into a Powerpoint. And, it's free! I think it would be fun to use in a Biology classroom, as you can link to pictures and text, and the Prezi is free flowing and visually attractive. I like how you can click on text to see a larger version of the text, and pan in and out to look at the overall picture, or the details. Gives you a lot of control over your work.
Here is an example of a great Prezi about "5 Steps to Success in Biology." Here is another great one on the Themes of Biology, which was created by high school students.