i second the motion to carry fix-a-flat. insanely usefull stuff. i keep 1 can in the car at all times and a second in my off-road camping kit. this should be in everyones car. i keep it bungee'd to my spare tire with 2 qts of spare oil behind the spare tire cover. a great out of the way place for it.

(still doesn't help on a tire blow out though....)