Camping is a small web framework, less than 4k, a little white blood cell in the vein of Rails. See it for yourself. Most camping apps are just one single file, packed full of Vitamins MVC and b12. A pocket full of tricks to free you of the globally namespaced doom of Sinatra, and the complexity of Rails. Camping and Rails are good friends though, so you can be sure if you ever outgrow your tent, Rails will help make your app the Next Big Thing™.
Camping has been around for a long time. It was originally one of _why’s projects. He wanted to write as small of a web framework as he could. I seem to recall that it used a lot of neat ruby tricks (overloading operators and meta-programming hacks).