Oh boy, the list is too long. In an official (paid) stntieg I've taken quite a few classes online. Accounting, all my personal finance classes, and others which I'm totally blanking on right now.Informally I've learned everything I know about any kind of website stuff. Social Media stuff. Everything I needed to know about starting a business and having employees. I think just basically everything I've needed to know in the last 10 years. And all for free!! It's amazing. I never really sat down and thought about it.