How Stuff Works
HowStuffWorks contains fascinating articles that explain how "stuff" - ranging from televisions to toilets to ultrasounds - work.
From car engines to search engines, from cell phones to stem cells, and thousands of subjects in between, HowStuffWorks has it covered. No topic is too big or too small for their expert editorial staff to unmask...or for you to understand. In addition to comprehensive articles, helpful graphics and informative videos walk you through every topic clearly, simply and objectively.
I use this site to find science videos. It's very useful.