Heterotopia of a nerd nouveau
For an upcoming project, I've written a couple of libraries for the Arduino board in conjunction with its Ethernet shield. Right now, there's a DHCP, DNS and a Bonjour library — Yes, Bonjour as in Zeroconf, the cool thing that lets your Mac automatically discover services on your network!
The DHCP and DNS libraries do exactly what you would expect. The Bonjour library lets you resolve Bonjour host names, discover and even register services running on your board. You might find this cool if you want to run a little web server displaying some sensor data, all while making it very easy to find the server from your Bonjour-enabled desktop computer.
I plan to add a couple of additional libraries in the future, but for now, the libraries as well as their, gasp, documentation are available under the GPL here. Have fun and make cool things!