I've been thinking about this "10 most important tool" one for a while now. (I'm taking for granted that, by your being in this forum, you mean tools for 'survival'). The 'best tools', I think, depend on your location and scenario. Surviving a car breakdown in New York City will have different 'survival' needs than a breakdown a few miles from of Fairbanks, Alaska. In the city, 'survival' might just be as simple as another battery for your cell phone (although I'd still keep some blankets in the trunk!). <br>I think shelter would be first. What kind of tools would help me build and maintain a shelter? I'd have some type of knife/saw. (Due to size limitations, I carry a folder with a locking knife blade and a saw. The RTAK would be much better than the knife I carry in some cases, but walking down some city streets with an RTAK on your belt will get you some interesting 'looks', especially by the cops. I'm aiming for something I can carry all the time, regardless of where I am). Some type of cord. Fire-starting supplies (matches, lighters, small candles, SparkLite & tinder) and fuel gathering tools. A tarp and some type of rope would be great to have, as would a sleeping bag or some blankets. A signal mirror and whistle are absolutes. <br>Second would be water. That means a way to store it (Keep a few bottles in the trunk), get and transport it (Nalgene bottles) and purify it (PUR filter/ Potable-Aqua), etc. <br>Third, food - Most people put food too high on their list. If you're like me, you've got enough food around your middle to last you for a few days, or in my case, a few weeks! :-) <br> I remember someone saying "You can't make an appointment to have an emergency." I figure if you don't have this stuff on you right now, you probably aren't going to have it on you when you need it most. I carry a pouch on my belt that is both small enough to carry every day, and yet big enough to actually be some help if I need it. In it are a Victorinox Rucksack knife, a Leatherman Supertool, a roll of thin nylon cord, a Sterling sharpener, a Spark-lite firestarter & a few pieces of tinder, 2 birthday candles, an extra flint rod, a Starflash 2x3 plastic mirror, an ACR whistle and an 3AA LED-type flashlight. I guess you could call them some of my 'most important tools' simply because I have them on me if I need them.