NiMC provides an Instant Messaging server and client that runs on a custom protocol that is implemented in python. The project was written as a learning experiment by its author, to get experience with TCP/IP. Great example of how to do TCP/IP wrong
A WebDAV browser and remote file editing framework written in Java, including an RFC-2518-compliant WEBDAV client library with optional SSL support, a low-level DAV command-line client (written in JPython), and a built-in text editing component.