This is something I've been building for about a year now, and it's really starting to come together. It's called Play My Code, and it allows you to create, and write games directly within the browser, with all of the tools and hosting provided for free.

The main focus for the site was to streamline the process of building a browser game. Today if you want to make a game using HTML5 and JavaScript, then first you have to find tools to use to write it, documentation to get you going, and write lots of boilerplate to setup the page. Next you need to find a way to get it online, and available for others to play. Finally it's very easy to write code which only works in one browser, requiring lots of testing. The site aims to streamline all of that, making the whole process of building a game in the browser as simple as possible. We also work around, or fix, many cross platform bugs, with the aim that our games will run in any HTML5 compliant browser (which is a lot more work then you think).

We have our own IDE, where you can write games and upload assets (so far images and sounds). We also use our own language, Quby, which is heavily influenced by Ruby. When it runs this is compiled to JavaScript, and again uses the HTML5 canvas for graphics. We have a 'sandbox' that you play in without signing up here, so you can get a look at the IDE, but you can also sign up to create and save projects online.

There are a bunch of games written so far, including a breakout clone, a rhythm action game, and lots more. You can also view the code and edit any of the published games (read only), allowing you to learn from examples, again without having to sign up.

But we still have a long way to go for making this more mature, so I'd be open to any feedback people can give!