When surviving, fire is the second most important thing. Fire allows you to boil water, stay warm, signal rescue workers etc.
Although lighters or matches are easy to use and generally cheap and readily available, if you are surviving in wet climates or long term, you are gonna want on of two items.
The first is fire steel. Fire steels are capable of lighting while wet, easy to use, and last thousands of strikes.
Here is an example: http://www.thinkgeek.com/gadgets/tools/754d/
The next way to make fire, which is by far my favourite, it a fire piston, a fire piston makes fire only using compression.
Here is a video by Youtube's: Cutlerylover