Antiweb
Antiweb is an event-based HTTP server that can support a high number of persistent connections in very small memory footprints. Antiweb is designed to support HTTP pipelining, uses vectored I/O operations to limit memory copying, and represents all data internally as UTF-8 even on non-Unicode supporting CL implementations. Unlike most other Common Lisp web servers, Antiweb features privilege-separated virtual hosts (with optional chroot support).

License: GPL3

Homepage: http://hoytech.com/antiweb/