I use travel soap dishes for a ton of things. They really are just the right size and the attached lid doesn't get lost!
Great tip... I just wanted to add that the kids plastic cups from restaurants work really well as crayon holders especially when traveling. They will fit into a cup-holder and the openings are big enough to see what crayon they are pulling out!
I've been getting so many spam comments lately, I've decided to disable "anonymous commenting" for a while. Sorry for any difficulty!