I wanted a way to test changes to the FlashPunk source in a reliable and repeatable manner, so I set up a testbed to showcase FlashPunk features. I hope more devs will contribute test worlds to make this as complete as possible.
It also has a gh-pages branch, which publishes the live version here.
http://useflashpunk.net/flashpunk-testbed/
Another cool thing about this is that it was compiled completely with the Apache Flex install, which is great since Adobe has stopped maintaining the ActionScript compiler.