Without a PC your best bet is buying a digital multitracker. Alot of them use zip drives for storage, and if you are or decide to record you're all set. Fostex and Alkai(I think)have multitrackers with zip storage, and I'm sure there are some keyboards that could do it as well.
Go to Musician's Friend or look in their catalog, I know they sell some units with zip storage. I hope this helps
Good Luck
Joe