I'd get the travel charger. We got them for our kids and they've been invaluable when traveling.
Celebrity Century 1/09
Carnival Destiny 10/07
Carnival Destiny 9/06
Monarch of the Seas 3/06
Carnival Inspiration 8/05
Carnival Miracle 4/05
Carnival Inspiration 4/04
Sovereign of the Seas 4/03
The charger is invaluable as ipod can be played while charging. There is no way (IF you have access to USB port) that you'd want to wait for unit to charge.
Also we have found foldable portable speakers for the ipod--small wattage (2?) that are perfect for in cabin chillin before dinner etc. Not loud enough to bother cabin next door but nice to have.
I know Fry's has them, radioshack etc.
Adventure of the Seas RC April 2008
Carnival Liberty April 2007
Carnival Miracle April 2005
Carnival Destiny June 2001, July 2005
NCL Southward June 1985 Honeymoon!