I've been hearing from some of my backpacking friends that they just can't find a commercially made fire starter that meets their weight (very light) requirements and burns for a long time (at least three minutes).  While I don't agree with them (as there are a lot of good commercial fire starters out there), I did tell them about a few ways that they could make light fire starters. 
     The first way is just by coating cotton balls with petroleum jelly.  What I do to make this happen, is scoop a hand full of the jelly out with your four fingers and rub your hands together to get the jelly all over your finger tips (yeah its a little messy).  Work the cotton balls between your petroleum jelly soaked fingers, and when the cotton ball is saturated you're done.  They are quick and easy to make.  To use this type of fire starter, work the cotton until one part of the ball (the center is best) is thin, very thin.  After this you just shoot sparks from your flint onto this thin spot (of course you can just use a match or lighter too!). 
     The second type of fire starter is a little easier to explain how to make, but it is more involved to make.  You will need an empty egg carton, some tea lights, dryer lint.  What you do is line a pot with foil (or just use an old one you don't care about), and put the wax (without the wicks) in the pot.  Turn on low heat and wait a little while for the wax to totally melt (melt about one tea light per carton slot you plan to fill with lint).  While that is melting, fill each slot of the empty egg carton with the dryer lint.  The more lint you put in the carton, the longer it will burn.  After the carton slots are filled and the wax is melted, pour the wax over the lint.  Note: put the carton on some foil because the wax will bleed through the bottom.  After you get the wax on the carton and lint, put the carton in the fridge (still sitting on the foil) and let it cool down.  After about 15 to 30 min the wax should be hardened again and ready to use.  Break off each of the slots of the carton and each one is one fire starter.  These usually burn for about three to five minutes, but I have had them burn up to eight minutes. 
     Hope this helps and good luck making fire starters!