I've always carried a little C02 device which instantly inflates tires (less than 3 seconds!)
I also carry a can of FLAT FIX which injects a sticky goo (to plug any leak) and C02 as a temporary fix
until I can make it to a service station.
I insist my daughters have these things in their cars and show them how to use it.
Most brand new vehicles in the last several years are practically immune to flats.
Older cars definitely need an emergency kit.
When it is least convenient, these emergencies occur.
Several products are on the market.
Perform due diligence on which product you select:
http://www.youtube.com/watch?v=82dB4XfUc-o
http://www.youtube.com/watch?v=xxOXPi6saAk