I had a fantastic run with no flats for years........... then it all happened, withing 2 rides I had 4 flats, I couldn't believe it!!!!! Two of them (on seperate rides) were in almost the exact spot. Since then I came up with the following:

1.  I run heavy duty tubes (well worth the money)

2.  When, or should I say if you get the chance, double skin the tubes by splitting an old tube and placing it as an outer liner in your wheel.

3.  Carry spare tubes, I currently carry an 18 and a 21, BUT you can get away with a 21 or a pair of 21's as you can run them in the rear (yes I have done it to get out of trouble)

4.  METZELER levers are the BEST!!!! 'nuff said!!

5.  I carry a 35mm film canister (yes the camera type) and have it full of dish washing liquid and tape it up to be doubly sure none leaks out.  This is to assist in getting the tire on and off.

6.  Also as backup I carry a small puncture repair kit, the style they sell in bicycle shops. While not 100% ideal they can do the job if you have time.

7.  I carry a telescopic bicycle pump, the kind that they sell for Mountain Bikes. These mean a bit of effort, but they perform the task. Also a fact that is not that well known at times is that the  CO2 cannisters don't usually blow up an entire wheel i.e. you have to use more than one to get adequate pressure, and a pump is a once off cost.

8.  A Gauge takes up little space but can be somewhat more accurate that the "feel method"

9.  Also despite the fact that you lose a little handling, when running in rocky or hard terrain I bump the pressures up to avoid puntures.

10.  Tighten your locknuts up against the valve caps, this stops the tube self destructing if it moves around!!

11.  Duct tape makes a good inner liner (the liner that covers the spoke ends)

12.  I have heard that some people carry 4 or more large hose clamps to put around the tire and rim to secure it in order to limp the bike home.  ( I haven't tried this though )
 

I've had little to no problems since I've implemented these measures.

My next step is trying Mousse tubes.
 

John K.

Notes on Re-occuring Flat Trouble - By Kloudkicker (from DRN forums):

When you get a flat, it's always a good idea to take a minute and figure out why you got the flat in the first place and go from there.

** Before you pull the tube out of the tire (and/or the tire off of the rim) use a marker or yellow tire crayon to indicate how the tire/tube/rim were arranged while together as a unit. This will help you locate where the trouble was after you locate the puncure(s) on the tube.
 

**Puncture Flat:Make sure you locate where the object came thought the tire & that the object is no longer there. Even if you do not see or feel anything, use a small phillips screw driver(punch or something close) and push it through the hole. Thorns, especially, have a nasty habbit of hiding in the rubber until their next opportune moment to bite your tube.
 

**Snake-Bite Flat: Indicated by a pair of puctures on the rim side of the tube. This is normally(but not always) an indication of not running a high enough tire pressure for the riding conditions (like really rocky terrain or traversing rocks with sharp edges).  I had a buddy who used to pinch-flat on RR tracks CONSTANTLY but would gripe that they were sucky tubes. Not quite.
 

**Blow-Out: If the tire looks fine, but the tube looks like it just caught a grenade.  My first guess would be that you over shot the triples again  Normally caused by an excessively high impact on the tire.

Other factors can be:
 

**Spoke Puncture: Indicated by a single hole on the rim-side of the tube. If your wheel is not double-walled(ie: the tube rests against the spoke nipples) this can be a factor for you. If the wheel has been 'brought back form the dead' or an slightly longer spoke got put in because it's what you had available, some spokes may be poking into the tube. The nipple itself can wear thru the tube also if not covered. I strongly recommend using heavy cloth rim-tape or hockey tape on the rim as a barrier between the rim and the tube(even if you do have a double walled rim). Rim tape will do it in one lap. 2 laps for hockey tape. Rubber rim liners move around on you when you least want it and lesser types of tape will wear thru faster than you might think.
 

**Nipple Hole Bite: Indicated by a ~1cm circle on the rim-side of the tube(double walled rims), the edge of which has the hole in the tube. Either you're not using rim tape or your using some form of substitute which isn't quite good enough. Keep in mind that the air pressure in the tire is going to try and push the tube into those little nipple holes if it gets a chance. As the tire and tube flex around, the edges wear through the tube. Heavy rim tape will prevent this from happening.

I think that covers the biggies.

If you have reoccurring trouble with pucture flats, I would strongly reccomend a tire liner. I've had really good results with them. Double tubing made the bike feel funny to me so I don't use that method. I do know a few people who love doing that though. Personal preferance.