It is very rare that I go so far off-topic on my blog, but then again, it is very rare that I find something so cool. Salman Khan (khanacademy.org) has recorded over 1500 mini-lectures on a wide variety of topics, organized in a cohesive fashion and made available for free on YouTube. I have already spent several enjoyable hours watching his videos, and plan on spending many more. What he has put together is an act of generosity that deserves to be recognized.
Feynman lectures on physics are very cool too.Along the same vein, the