A volcano storm over Mount Chaiten in Chile.
I’m not sure how to top that really 
Spectacular! Sometimes you’ll see sporadic lightning associated with an eruption, but this combination of plume and storm is awesome indeed.
Here’s an explanation of what might be going on with the eruption-inspired bolts.
Way cool, Pushkin.
Interesting, and as if fleeing an eruption wasn’t terrifying enough already 
That’s, like, pirate-with-a-ninja-sword-cool.
OOOOO! That is very, very cool.
Wow.
There are a few seconds of video in this youtube video of the lightning in the volcano clouds. Not as good as the still images though.