* Fruit yogurt with packets of sugar mixed in makes an easy-to-obtain gentle, yummy-smelling, moisturizing, exfoliating mask.
* Fabric softener dryer sheets tucked into the lining or pockets of suitcases keep your clothes fresh when packed and have many other uses for which they can be diverted if needed. They can be used in a pinch to eliminate static cling by rubbing them on a garment. If you need to use a hotel washer/dryer, they usually have detergent available, but seldom softener, but you have your own on hand. And if your shoes are a little rank, you can stuff them inside to freshen things up overnight.
* Jojoba oil is very versatile to have on hand because you can use it as a moisturizer for your face, body, or hair; if your hair is dry or frizzy in a different climate you can rub it on the ends before bed as a deep overnight conditioner, add a couple drops to your conditioner, or smooth a little through damp hair before blow drying as a leave-in conditioner. I also really like the Aveda oils like the balancing infusion and beautifying formula for similar reasons; very versatile and can fill in for a number of other products or fix beauty problems resulting from being in different climates and using different types of water.
* Hotel shampoo makes good bath gel or bubble bath. You can also wash a garment with it in the sink in an emergency.
* Hotel mouthwash is great for freshening your toothbrush after its been in a travel tube if you pour it into a glass with enough very hot water to cover the bristles and soak it overnight.
* Many gas stations still sell 2.5 ounce spray deoderents that are small enough to fit into a quart size baggie with your other toiletries (especially if you take the top off). This size is very hard to find anywhere but gas stations.
* A little milk poured in a tub makes a nice milk bath.
* Chanel eyeshadows can be used wet or dry. Most of the compacts that have 4 colors include a black or at least some pretty dark color. When I forgot my eyeliner and mascara, I wet my the tip of my eyeshadow brush, dipped it in the black eyeshadow and swirled it around gently, and carefully lined my eyes and colored my lashes with it. It worked like a charm. What a handy product!
* Chanel is very generous with skincare samples. I never buy anything from them or any other counter without asking for samples of the same thing I am purchasing, "for travel". I don't want random samples, I want the ones I really use, and they are usually very accommodating (probably because they know their stuff is expensive). I also love their little sample perfume bottles that have the little roller balls, they're so cute, take up no room, and one will last for several trips.
* GloMinerals pressed powder base is amazing and it works as both a foundation and a touch up powder. I never carry liquid foundation anymore and I think the mineral makeup looks much more natural and holds up better to long flights.
* I sometimes put my good shampoo and conditioner into emptied out hotel shampoo and conditioner bottles so that when I have used them all up during the trip I can just toss them out and don't have to drag the empty bottles back home with me.
* It is always good to have an extra pair of clean underwear, even at the end of trip. You never know when you'll get stuck unexpectedly and that's the one thing you really can't just wear over again.
I've typed way too much but I kinda got carried away on this post...