Well, I’m quite interested in science, so that I mostly work on scientific stuff with Blender. Here are some of my finished projects (I’m quite new to Blender, so please don’t expect miracles ;))
solar eclipse - http://www.youtube.com/watch?v=yi5gcD_jot8
translation - http://www.youtube.com/watch?v=auEfcmufRgI
fertilization - http://www.youtube.com/watch?v=JIKRzbSgYgc
first steps of mitosis (more or less 2D-like) - http://www.youtube.com/watch?v=wnUhs4QVIcU