Did you know that plastic bottle caps are not accepted at some recycling centers? They are made from a type of plastic (#5) called polypropylene. You can check Earth911 to see what type of recycling is available in your area. It says my local Whole Foods accepts #5 plastic (and even Brita filters!) Also worth looking into is Recycle Caps with Aveda is a program in which caps are collected throughout the community, by salons, in school, etc. and then made into caps for Aveda products.
Kiwi magazine has a great idea for repurposing plastic caps. I would love to find more ideas like this!
Go here to see the directions for making these super-fun magnets!