GoESMTP is a multi-node ESMTP server. It was designed from the start to work as a cluster. Each node keeps an index of the available messages by using hashes which are distributed throughout the cluster.
dht is an implementation of the BitTorrent "mainline" Kademlia DHT, used in particular by Transmission, Shareaza, and Hekate.
Forth for the AVR Atmega microcontroller.
A PHP/MySQL guestbook script.