M.I.T. offers http://ocw.mit.edu/OcwWeb/web/courses/courses/ with a wide variety of courses to learn something new, rattle those marbles in your brain around and fine tune what may (or may not) be there.
or this one: http://web.sls.csail.mit.edu/lectures/
learner.org also has some fun things presented by the Annenberg Foundation.
more at Texas University at http://web.austin.utexas.edu/wlh/index.cfm and http://lecturefox.com/
Duke University has a series of lectures available for download on iTunes.http://deimos3.apple.com/WebObjects/Core.woa/Browse/new.duke.edu.1301297093.01301297103