'Flat fixes' specialize in, well, you guessed it, fixing flats. I'm not sure whether they exist outside New York or not. I only heard of them since moving to Brooklyn.
A whole slew of them exist here, because the streets are so terrible. Cars park in the street and have their bum tires repaired within a minute, for a nominal fee.
If you ever intend on driving in New York, good luck. Mark has gone through two tires and several puncture repairs this year.
Related posts: Taxi Driver, Safety and Taxi!.