Make an extra one to keep in your saddle bag and you'll always have a few spare chain links if you ever break a chain while away from home.
Step 1: Break the Chain
Step 2: Join the Ends of Your Opener
I have seen another site online that recommended joining the 2 ends of a bike chain with a split-ring key ring to make a keychain. this is a good idea, but makes for a bulkier item in you pocket. I prefer the simple loop of chain.