I'm pretty sure I've heard this before, but I'd forgotten. Did you know that MIT offers virtually ALL of their course materials online for FREE?
I'm not sure exactly how it works, but I started with this list of courses and started browsing. There are some very interesting things there. I'm posting this here primarily for me, so I'll remember this time. I know there's something I'll enjoy learning.
If you're interested in learning something new, or taking a refresher on something you've already learned, be sure to check it out.
Another source for free online courses - Edex.org .
I'm checking them all out!