I just released the lonely and poor httpd. Its not
RFC full-featured but was written as a study for
a single-threaded, high-speed HTTP server which
can handle tens of thousands connections simultaneously.
It delivers static content, supports vhosts and autoindexing
on the fly. It doesnt need any config-file and runs
as nobody in a chroot for maximum security :)
It avoids unnecessary userland/kernelland/socket-buffer copies
by using sendfile(2).
I tested it on Linux and FreeBSD. As long as your OS supports
sendfile(2), it should be easily portable.