RootPrompt points to a Security Focus article on creating open source honeypots:
Honeypots are an exciting new technology. They allow us to turn the tables on the bad guys, we can take the initiative. In the past several years there has been growing interest in exactly what this technology is and how it works. The purpose of this paper is to introduce you to honeypots and demonstrate their capabilities. We will begin by discussing what a honeypot is and how it works, then go into detail using the OpenSource solution Honeyd.