These links were passed along through a homeschool group to which I belong. I've never used these resources, but they look interesting:
EDUCERE K-12
http://educere.net/
FREE COURSES FROM CARNEGIE MELLON
http://www.cmu.edu/oli/
And now for some HOMESCHOOL HUMOR:
http://www.geocities.com/tankgrrl360/hs_humour.htm