Client-side Web REPL For 15+ Languages

In his first accepted submission, MaxShaw writes "repl.it is an online REPL that supports running code in 15+ languages, from Ruby to Scheme to QBasic, in the browser. It is intended as a tool for learning new languages and experimenting with code on the go. All the code is open sourced under the MIT license and available from GitHub." A few of the languages are supported by reusing existing "Foolang in Javascript" interpreters, but a number of them are built using Emscripten (previously used to build Doom for the browser). All evaluation occurs client side, but saved sessions are stored on their server.