Here's a nature/biology favourite of mine:
http://www.hww.ca/index_e.asp

And a fun chemistry one (v. popular here):
http://www.periodicvideos.com/nyt/index.htm#

A history of Ancient Greek science site:
http://www.mlahanas.de/Greeks/Greeks.htm

Some engineering lesson plans (haven't tried any yet, but they look cool):
http://www.tryengineering.org/lesson.php?from=8&to=&cat_id=&keyword=

Some neat-looking optics resources:
http://www.micro.magnet.fsu.edu/optics/tutorials/index.html

I need to go finish my Christmas sewing....

peace
minnie