Someone mentioned above that if you have a gas stations nearby with free air, that this could be a substitute for having a pump. Just a word of caution that this is only an option if your bike has Schrader valves. I've yet to encounter a gas station air chuck that would handle Presta valves.

I know this because years ago when I purchased a bike the salesman asked me if I needed a floor pump. I told him no, as I had an air compressor at home and just figured I'd use that to pump up my tires. Later when I discovered that my tires had this weird air valve I'd never seen before, I was back at the LBS sheepishly asking to see their floor pumps.