I just had a great idea for zombie apocalypse equipment: glow sticks!  They're light, cheap, and waterproof, easy to break on purpose but hard otherwise, and they give off a surprising amount of light.  You can throw them into a room to check for and distract infected, set one up as a beacon, or do any number of other things with them.  If you get a lot of little ones, you can even set a trail for your friends.  Plus, you can make weak ones with some basic chemicals.  But I wonder... what would it be like to paint with one of these?  Painting with a stick of sunshine... I like the idea.