Unfortunately we still aren't quite there yet, although just about everything else has been ported to run on javascript: https://github.com/jashkenas/coffee-script/wiki/List-of-lang...

And making basic/visual basic on top of javascript is a little challenging since it is case-insensitive and statically typed (later versions).

But I'd especially recommend Scratch from MIT for kids: http://scratch.mit.edu/ Many people are working on ports or similar tools in flash and html5, but none are quite there yet.

Also see the game Light Bot (1 or 2): http://www.silvergames.com/light-bot-2

And for older folks, some nice in browser development sites include http://www.playmycode.com/ (uses a ruby-like language) and http://pixieengine.com/ (uses coffeescript)

And for making websites see kodingen.com or playing with javascript, see jsfiddle or jsdo.it or processingjs.

For those of us who grew up with QBasic: http://stevehanov.ca/blog/index.php?id=92