For Hack Week, Jonathan Pobst did a pretty cool hack: he added support for Banshee to work with the Nike+ Accessory on iPods.
From his blog:
I decided that part of my Hack Week would be to venture from my "happy place" of Winforms in Visual Studio and write something in GTK# using MonoDevelop. I chose to write a plugin for Banshee that allows it to sync with and display files generated by taking your iPod for a run with the Nike+ accessory. Oh, and using Moonlight, just because it seemed fashionable.