Great for non-food items! Mama taught me this.
This is my on-the-go medicine cabinet. Works great. I cut up the packaging, leaving the important information, and put that along with the medicine and instructions inside a sandwich sized zip bag. I have Rx for allergies, mild/severe colds, mild/severe stomach irritations, general pain killers, indigestion. I also have masks, cough drops and pocket warmers in there. All of these things go in one giant zip which goes in my suitcase. It takes up very little space. The zip bags are low friction, so they're real easy to sort through when taken out and put on a bed or table.
I get to travel here and there sometimes, so I have lots of loose change and things of the sort from different countries. Everything goes in its own marked zip bag. Since I am in Japan quite often, I have an old wallet I use just for Japan. All of these things, including passport and other travel documents go in an old iBook neoprene bag with my name (designed by Mama) on it.