Depends on where I'm going, and what you count as a 'device,' but usually I have my HTC G1, Kindle DX, and Macbook 13" Unibody. If you want to count large bluetooth headphones, I also usually carry a pair of Motorola S805s, and if you want to count portable hard drives, I have a 250GB drive in my bag as well. I think there are some other things in there too, like a small usb hub.
I don't think that the pandora will replace any of those things, but if it would allow me to not carry the bag, then that'd be great.