I stumbled across
Dot.iTunes, an application that turns your desktop computer into a server for your iPhone/iPod.
Basically, it allows you to access your iTunes library that is stored on your home computer (Windows or Mac) and stream it across the internet to your iPod/iPhone.
This is great, since it breaks the memory and storage limitation to your iPod or iPhone. Essentially, your iTunes application becomes a web server that is accessible from anywhere on the planet.
I'm just testing this app out right now. I'll give a more complete report on it later. Anyone using it right now?