I actually had a B 2 bomber in a game I just finished. Without intending to create it, it just came about :-) It formed gradually between moves 70 and 192. And sure enough, I would've won if I hadn't misread the board and resigned while ahead at move 273. >_<

Moves 191 to 192  

End of the game. Move 273  

Seeing that white's move saved that big group in the middle, I mistakenly thought it gave white the victory. Later I realized that I was still ahead, just not by as much. >_< (At this point, I had 21 prisoners, and white had 7; it was a 4-stone handicap game)