From the announcement of the open source reddit:
There are only five of us who work on reddit; we couldn’t have made this site if it weren’t for a great community of developers. In no particular order, here’s a quick list of the open source products that reddit is built and runs upon: Debian, lighttpd, HAProxy, PostgreSQL, Slony-I, various python libraries, Psychopg, pylons, Solr, Tomcat, Ganglia, Mercurial, Git, gettext (translation), daemontools, and memcached.
Five people. 1,000,000’s of pages every day.
