What Darwin never knew

This is an excellent general overview of evolution by natural selection, care of NOVA.  It explains how Darwin started thinking about why animals are so diverse, and came to his brilliant conclusions.  It then goes on to explain basic genetics, gene expression, and embryo development.  For anyone unclear on how evolution works, or especially anyone skeptical that evolution by natural selection does indeed occur, I highly recommend the video.  For that matter, it is a good reminder to those who work in genetic engineering:  there is much more to the genome than simply the relatively few genes that we see expressed, much that we don't understand.  This should certainly be cause for humility for anyone who thinks himself master of genetics, simply because he's figured out the function of a few genes, or can even transfer individual genes from one place to another.