If you love the convenience of thumb drive but need something a little roomier, check out Pocketec's upcoming Nano drive. This hard drive-based unit measures about 1-inch squared, and has all of 12GB of storage on board. You can get that much with flash drives, but you'd have to cough up hundreds of bucks.
Of course, having 12GB of your personal files and pictures on this means you'd better hold onto this or else run the risk of having your "vacation" pictures posted on the internet.
Update: You can buy one here for $169. Thanks Michael!