I actually brought something out of the $.99 store that is perfect for holding stuff during sea days. It was a camera holder I think but it works perfectly because there are little mesh pockets on the outside for stuff (lipstick/lighter/gum) and on the inside is a slim compartment perfect for sail & sign/credit card/license with a larger compartment that holds anything about the size of a disposable camera. It has a velcro flap cover. I also bring something very similar to this but larger with more slots/compartments when I go ashore at the port stops. I don't remember where I got the the second one but probably a walmart/kmart like store for just a few dollars.
I fly to the ship so I carry a rather large shoulder bag on the plane. When I get to the room, I put the important stuff (credit cards, passport, etc.) in the safe and just leave the shoulder bag in my luggage.
Do try your local $1.00 store first.
(cruzin' solo by design)
Freedom ('09), Imagination ('08), Victory ('08), Destiny ('08), RCCL Navigator ('08), RCCL Majesty ('08), Glory ('07), Liberty ('07), Fantasy ('07), Destiny ('06), NCL PofAm ('05), Fascination ('04), Victory ('04), Fascination ('04), RCCL Voyager ('03), Fantasy ('99)