these things are great, and they saved my life! due to an overweight suitcase on my last vacation, i sacrificed my shampoo & conditioner, planning on using whatever the hotel provided, which didn't work out. i ran around disney world like a lunatic hoping for some solution & i found it at the Basin store in downtown disney. these are soap-like bars, but they're shampoo and conditioner. you can rub them between your hands and then wash your hair, or rub them directly on your scalp/hair (which is far more efficient, btw). they have a wide selection of scents & claims from color preservation to maximum hydration to volume, etc. what i really love about these is the convenience -- because they're solid, you don't have to follow the airline liquids rule. these are a staple in my travel bag and i highly recommend them.
for a more detailed review & direct links to the Basin and their products:
http://hewhocravestherose.blogspot.com/2012/06/this-has-got-to-be-niftiest-thing-ive.html