I like building platforms and libraries in JavaScript.
You can check out my GitHub repos here: https://github.com/asmblah/ Have a play with my JavaScript x86 emulator here: http://jemul8.com (https://github.com/asmblah/jemul8) Or see how you can run PHP in the browser (or Node.js) here: https://github.com/asmblah/uniter Feel free to get in touch: dan [at] ovms.co
Cheers!