well how about one of those cans of get you home tyre repair stuff that name completely escapes me at the moment. it goes in and reapirs the hole and then said gunk inflates the tyre. Some cars now come with a can of that instead of a spare wheel.
Always carry the stuff on my motorbike on any longer trips. But it doesn't always help. If the puncture is a big enough cut, the spray stuff won't seal/fill enough.