Teapot is a project mainly written in Perl, it's free.
An RFC2324-compliant webapp
Implements the parts of rfc2324 that matter if you are a webserver who feels like impersonating a teapot, or if you would like to have a webserver that behaves thusly, or if the machine is actually connected to a teapot, or.. countless other reasons, I'm sure.
Requires Perl, and Dancer.
Not recommended, since the RFC needs HTTP/1.1 and the embedded webserver is only able to emulate HTTP/1.0.
$ ./teapot.pl
>> Dancer 1.3014 server 31928 listening on http://0.0.0.0:3000
== Entering the development dance floor ...Recommended, since it accepts HTTP/1.1 requests.
$ plackup teapot.pl
HTTP::Server::PSGI: Accepting connections at http://0:5000/In my tea?! WHERE?!
Dancer, Plackup.