A while ago, someone tried to pitch to me the idea of an in-browser collaborative IDE which you could use to build web apps without ever leaving the browser or

A while ago, someone tried to pitch to me the idea of an in-browser collaborative IDE which you could use to build web apps without ever leaving the browser or even setting up...well, anything, really. I didn't think it would work due to security implications, but it looks like you have solved that problem. You have what amount to project-specific VMs which can presumably run web servers. You have a secure collaboration setup. Imagine a group of people who want to implement a web app. All they have to do is buy a private server from you, which already has software to allow them to write and serve code. If you nail the IDE, then the web app development process becomes much, much closer to the "normal" method of write/compile/run. In your case, it's write/save/refresh other page. I realize that you are focusing purely on the REPL right now, but you got me thinking about it and I wanted to share. If you turned these babies into web servers too, it would be pretty awesome. You'd probably have to move to "cloud" hosting, though. Anyway, great app. I'll probably be using it. But I resent your categorization of Python and Ruby, and agree with gcampbell's UI gripe.