[AcerbicZero]

I was (and still am) a huge fan of repl.it, and I used it heavily while I was teaching myself Python/Ruby a few years ago. Being able to type code, in small chunks, and test anything that didn't work as expected is a massive help when picking up a new language, for me anyway.

I stopped using it when I switched jobs and our proxy was breaking connections to the site, but it looks like it has come a long way since then.