TSA: Permitted and Prohibited Items
Includes a list of items permitted on airplanes as well as prohibited items. From the Transportation Security Administration.
Packing tips for carry-on-only trips.
Universal Packing List
From things to do before you leave to sections on clothing, equipment, hygiene, health, and more. Includes comments and tips from travelers.
Rick's Packing List
Packing list essentials from travel guru Rick Steves. Includes a simple list of what to pack for any trip.
Compleat Carry-On Traveler
Opinions and ideas on the art of travel with an emphasis on living out of one carry-on-sized bag, by Doug Dyment.