These are available in a variety of sizes and thicknesses and the smaller, thinner versions are very light and pack into a small roll.
Second, a flashlight. There are very small single AA cell LED lights that are bright, the battery lasts a long time and the bulb lasts nearly forever. An LED headlight can be substituted if you want to read at night.
One other omission: a towel. Get one of the quick drying microfiber synthetic types made for back packers as they are also small and light but quite effective.
This message was edited by DaveB on 6-3-07 @ 5:55 PM