My favourite tool to share a directory over http is boa. However, new options are always welcome, more so when it is a simple script. A developer has shared such a script that uses CGI to share a directory as a webserver.
To use the script and serve a directory as a HTTP server, run:
$ curl -L http://tinyurl.com/servesh1 | sh
The script is published as a GitHub gist and you can go thorugh it here.