Originally posted by fore
carry a chain tool. if your chain breaks, turn your bike into a singlespeed.
No need to be that drastic. Just remove a full link. You may not be able to shift into the big-big gear, but I'd bet the rest of them would work OK.
I stopped carrying a chaintool for a while but recently the chain started to separate and I was lucky it didn't completely fall apart before I got home.