I have three, 3G 15GB, 2G 4GB mini, 512MB shuffle, and I still want more.
I'd like to replace the 15GB 3G with a 60GB 5G for portable jukebox, music library and portable video duties and also replace the mini with a 2GB or 4GB nano as my primary portable music device. The shuffle would maintain thumbdrive/skiing music status.
I finally got my hands on a nano the other day - my sister's bf got one so I had a play around with it and it is a stunner. The menus are so damned quick and the screen, whilst very small is surprisingly clear, detailed and easy to read.