Wookie
Wookie is an asynchronous HTTP server built on top of cl-async. Wookie has a focus on writing web applications. It can also easily be used for quick, one-off websites but its asynchronous nature may be challenging for this use-case (see Hunchentoot for a great alternative).

Wookie has a plugin architecture, making it easy to extend in various ways.

License: MIT

Homepage and documentation: wookie.beeets.com/. Note that this doc site is built on top of Wookie, and its source may be a good reference.