Last year a guy got rescued in Scotland by using his Cellphone Camera Flash to signal a helicopter in very poor weather. I think it was from another thread on the forum that I found that newspaper article.

Also in Wales they used the back light from a Cellphone to allow the helicopter to get closer in poor visibility to rescue an entire group stranded in a bog.

http://www.northwaleschronicle.co.uk/new...m-hillside.aspx

So it really does work, improvisation will keep you alive in the wilderness.