There was some one on the web taht dunked his nano into beer (On purpose even) and it still worked. the nano is suposed to be very rugged.
2.4gHz 15" MacBook Pro, 1.66gHz Core Duo Mac Mini, 2.5gHz G5 QUAD, 733mHz Quicksilver, 450mHz G4 Cube, 700mHz G3 iBook, 350mHz Sawtooth G4, 350mHz Revs. A and B B&W G3, 16mHz Powerbook 100, 8mHz Macitosh Classic.