Hairball is an HTTP server and framework designed for the realtime web written entirely in (common lisp).

It doesn't do much, but it does support long polling requests, it's single threaded, and it's fun to use. It's not suitable for making real applications, so if you're thinking of using it for that, you're crazy. One day...

Included along with the framework is a group chat application (see the live demo) and a simple hello world (below).