Free Chemistry Courses

http://askthenerd.com/chemistryonline/COL-2.html

This site includes 3 courses: Intro, General, and Organic chemistry. The lectures require a login. The lecture slides, though, make a nice course and are free, as is the textbook, worksheets with answers, and other materials.  Definitely college level, but not complicated.

Black Holes

This is an awesome lesson on Black Holes, complete with a journey to a couple of different black holes.  Animated, accurate, and interesting.

http://hubblesite.org/explore_astronomy/black_holes/home.html