Online Course Reviews
It's amazing how many free courses are out there. If you have even the slightest bit of interest in a topic, there's usually zero committment in taking the class. If you lose interest, you can always just drop the course.
Here are my reviews of the courses I've taken so far. The short version is that I'd recommend any of them.
CS188x: Artificial Intelligence (through edX)
I have to admit - I ended up dropping this class near the end. The workload towards the tail end increases dramatically and I had just started a new job.
Be aware that, towards the end, you are going to need to devote significant time to understanding the material and completing the assignments.
Even though I ended up dropping the course, I feel like I got a lot out of it. After spending a decade in the trenches, it was nice to get a bit of a reboot and look at things from a CS perspective (as opposed to a software engineering perspective) again.
Functional Programming in Scala (through Coursera)
Scala is an interesting language. I don't know if I'll ever end up using it professionally, but it has a lot of features that are fun and interesting.
For years, I've been leveraging some concepts from functional programming in my imperative object-oriented code (e.g., increasingly favoring immutable objects and collections) but it was nice to get a more formal introduction into purely functional approaches to problem solving.
Unlike the AI course above, there's no sudden increase in time requirements and I was able to stay consistently about two weeks ahead of the deadlines with just a few hours committed every week.
Rails for Zombies (through codeschool)
Unlike the other two, this has a very limited scope. This is a tutorial on how to get started with Ruby on Rails.
I don't think you'll be a better programmer for having taken this course - it's not going to help you if you working in another language or framework.
That said, I think it accomplishes its goals very effectively. It's entertaining and very approachable. I'd highly recommend it for seasoned programmers looking to learn Rails or beginners looking to learn some server side web development.