Not to detract from what is a pretty cool project, and I hope OP had fun making it, but: http://codepen.io is this and quite a bit more. It supports HTML+JS+CSS as well as e.g. Jade, SASS and CoffeeScript- if that's what floats your boat- and some nice social features, like featured pens and saving to Gists.

Other commenters have pointed out a myriad of similar such services. I'm surprised Codepen hasn't come up already.

@brycecolquitt, you are obviously very talented, and I look forward to whatever you come up with in the future. I just hope it's not in a space as hotly contested as this.