[toss1]

It is very cool.

While he's possibly the first to think of it in a photography context, I have heard of an ice lens being recommended in a survival context -- fashion a lens to start a fire with the sun.

I've had no idea if it is actually practical; I'm sure you'd need some very good dry & fluffy tinder. This photo experiment tilts it much further into the 'Plausible' zone.

[lultimouomo]

Mythbusters tried this and got some smoke, but IIRC not actual flames. Seemed to be pretty possible though.

[moron4hire]

I can see that being possible. Cold, winter air is very dry. And frozen water doesn't tend to seep into things.