NIO is non-blocking i/o (with cffi) for CL. Non-blocking I/O allows faster serving of e.g. web pages, see http://www.kegel.com/c10k.html.
There's a trac available at http://trac.common-lisp.net/nio.
[9.10.2006] The 2006-01-22 version was leaking memory, please use version from svn or apply the supplied patch (see Downloads).
NIO-HTTPD is a example http server which currently serves (hardcoded) static / dynamic pages. It works at least with OpenMCL / Mac OS X and SBCL / Linux 2.6.
Basic API for event notification and asynchronous (socket) i/o is implemented.
See brief_api.html for brief description of API.
nio-2006-01-22.tar.gz - cvs checkout in .tar.gz
Anonymous checkout available via:
svn checkout svn://common-lisp.net/project/nio/svn