I wrote last year about the Khan Academy over at The Voice of the DBA blog. It's a resource that one man set up for his kid and it has grown into a great learning resource for a number of academic subjects. It's a great resource, and if you have kids, check it out.
However, if you're interested in being a teacher in one of those subjects, it's also a good resource. You could get background on a subject, view how others teach the topic, or brush up on portions of the subject you aren't familiar with. That's in addition to being a great teaching tool.
In my industry, the SQL Server/data professional field, we have tons of resources available to us. Microsoft provides various hands-on labs. The company I started provides daily resources to learn from. There are plenty of other resources as well, including free events, and webinars from a variety of sources.
I know the tech industry is probably ahead of others, but more and more doctors, lawyers, and others are blogging and providing free or cheap education all the time. You just have to look for it.
Take control of your career, and seek out resources that can help you get better, learn new skills, and hopefully find the best job in the world for you.