CodePen is a playground for the front end side of the web. It’s all about inspiration, education, and sharing. Need to build a reduced test case to demonstrate and figure out a bug? CodePen is great for that. Want to show off your latest creation and get feedback from your peers? CodePen is great for that.
These are The Most Popular Pens of 2013, as decided by their super fancy algorithm modified without the age penalty. All of them are very impressive, and I am sure you can learn something from them.