Tampons make really fantastic survival items. They may not have as many uses as some other items, but they uses they do have are very important.
They are made of cotton, so they make great Tinder for fire starting and will catch a spark easily if you fluff them out a bit. They can even be charred in a char tin (refer to my book on fire starting for more info on char materials) to make it catch a spark much easier. You can also add Vaseline or Chapstick and rub it in to the fibers for a dramatically extended burn time.
Tampons are also sterile making them perfect for medical applications. Simply unroll the tampon and tape or tie over your wound and you have a sterile dressing.
Tampons are also great for use in primitive water filtration systems. Simply unroll and fluff them up and then stuff them into the neck of an upside down bottle with the bottom cut off. Then add some powdered charcoal and some sand if you can find it, and you have a water filter. This removes sediment and gets water cleaner and ready to boil. A little tip for you if your filter is running too fast is to leave the cap on the bottle and pierce a hole in it to slow down the flow.
Tampon wrappers are waterproof and can be used for storing matches or tinder inside. If you need something to secure the end of the tampon packet you can use the string from the tampon to tie the end. Obviously as the wrappers are also waterproof this also means they are airtight so can be used to make floats for fishing.
They can even be used to make slow burning candles. Simply roll some of the fibers into a small wick and dip into some liquid fuel in a small dish, tea light case, metal bottle cap or whatever else you can find and light the end. The string can also be used but will burn quite quickly in comparison.