I absolutely love the series of math and geometry videos that Vi Hart has published.  If only I could find a “slow motion” button to catch it all as she speaks…

About Vi Hart from Wikipedia:

Vi is the daughter of mathematical sculptor George W. Hart and his former wife Carol Hart. Vi credits her largest influence to a trip she took with her father when she was 13. She attended a computational geometry conference with him, and claimed she was hooked to math from that point on. In an interview, she stated that “It was so different from school, where you are surrounded by this drudgery and no one is excited about it. Any gathering of passionate people is fun, really no matter what they’re doing.”