Tried this stuff - Tactical Nuclear Penguin. It's actually really nice, like a sort of smoky whisky in a way.
But it's not the strongest beer anymore - Brewdog had a sort of face-off with a german brewery where they made progressively stronger beers. Brewdog made one called "Sink the Bismarck", the german guys made another, then Brewdog made "The End of History" 55%,
then Brewdog made some other guys made "Armageddon" - I think it's 65% ABV or something ridiculous, that's the strongest at the moment
I think EDIT: Brewdog actually make some amazing "normal" beer, their Punk IPA and Hardcore IPA are both excellent.