CodePen has an impressive amount of support for preprocessors (such as Jade, Haml, Slim, Sass, Less, Stylus, Coffeescript and PostCSS). There is also plenty of frameworks and libraries to pick from (Foundation, Bootstrap, Angular, D3, Backbone, Ember etc.).
The codepen profile page allows you to display all of your public pens, and control which order you want them to be viewed in. This is great for showing off your work to possible employers, other devs etc..
On running an SQL statement the URL is updated to give a unique URL corresponding with your query. This can then be shared with others to allow them to view, run, and amend your query.