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..
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.).