I have cheapo peanut lighters from Dealextreme.com. They're sitting on a shelf and have held fuel for about 2 years and still going. I only light them about once every 6 months for kicks. I have to say that all this talk about fuel eventually running out of a peanut lighter, I have yet to experience it. I don't deny that it will happen. It just hasn't happened yet for my peanut lighters.
Let me check again right now... Yep, they still light up. In fact, they're still saturated with the fuel I put in there.
For that test in the link above, note the guy was lighting up his lighters EVERY week. So,
the fuel ran out of the peanut lighters after 59 weeks probably because he was using them, not because they were leaking. Also, we can't say if his O-ring was in shape. 59 weeks is great, but again mine still light up after 2 years of rarely lighting up my peanut lighters.
Bottom line, a peanut lighter can serve as a damn reliable backup firestarter, especially if you hardly ever use it.