https://rubymonk.com/ is another good one. The theme got a little tiresome after a while but the lessons really forced me to mess around with Ruby in the console. I learned a lot.

It's a bummer that division is not going to be supported in ES9, but boson() seems really useful ;)

A lot of funny stuff there, this was my favorite:

Describe your location:

Cool East London Quirky Stylish

(If it's anything other than these, please consider relocating your offices)

I'm offended

"In 2010, Facebook acquired the FB.com domain name for $8.5 million."

Wow. And to think they only bought facebook.com for around $200k if I remember correctly.