I love TED (Even if some of their lectures are a little odd occasionally).
There's a few others that should be on everyone's regular reading (/viewing) list:
http://documentaryheaven.com/A huge library of documentaries of all sorts on all subjects.
http://ocw.mit.edu/index.htm2000 video and text courses on science & engineering subjects from MIT.
http://www.badscience.net/Ben Goldacre's one man campaign for better understanding and more accurate usage of science. The articles linked in the mini-blog are usually mindblowing too. The forum (and its community) is an amazing resource for anyone with an enquiring mind.