Saw this over on Bushcraft USA. Seems a cool way to get a bit of light and drain your tuna (if it's in oil). Tuna's good to eat after, as well:
http://www.youtube.com/watch?v=qSN4_V22T00&feature=player_embedded#!
http://www.youtube.com/watch?v=qSN4_V22T00&feature=player_embedded#!