This one may seem a bit unnecessary, but savvy cruisers will tell you that you'll be glad you thought to pack a power strip in your carry-on bag. Most cruise ship cabins are short on electrical outlets. There may be one in the bedroom and one in the bath and you can't be guaranteed of its placement. A power strip will ensure you can easily power up or recharge your own alarm clock, a reading lamp, an iPod and speaker set or your cell phone. If you really want to go the extra mile, bring along a 10-foot (3-meter) extension cord to use with the power strip. This way you can tuck it under the bed and out of sight. Another thing a power strip and extension cord will allow is the luxury of operating your own small coffee maker. As any java addict will tell you, having a fresh cup of your favorite blend as soon as you wake up is worth the extra space it takes up in your luggage.