Httpd is a modern httpd for Inferno. It supports HTTP/1.0 and HTTP/1.1, virtual hosting, CGI and SCGI, logging, index file serving for directories, and directory listings, has configurable MIME types, understands range and conditional requests, does HTTP Basic authentication, and supports redirections based on regular expressions.
sh-httpd is a shell script-based Web server that supports GET and HEAD methods, and a CGI 1.1 interface. It's not real fast, and it's probably not real secure, but it is really small. The Web server and it's configuration files are around 9,000 bytes total, and that's with comments and pretty whitespace. If you can run ash or bash, an inetd, and about 7 standard external commands on your system, you can have a Web server with CGI support. There's also a timeout counter that kills never-ending CGI programs, cleans up, and exits.
Pygmy is a tiny HTTP 1.1-compliant Web server written for the purpose of embedding into applications. It implements both HTTP and HTTPS, and supports extension through a plugin architecture and flexible configuration. It can scale in functionality as needed and compress to under 40KB.