I may have got this URL here, but in case I didn't, here is a dandy for your favorites.

http://www.bestcollegesonline.com/blog/2009/06/18/100-incredible-lectures-from-the-worlds-top-scientists/

Yeah, I forgot, so I sent some soil from my backyard in for analysis. Today the results came back and I found out that the dirt is sixty four. Nuf said.