I am a big fan of using Do Something Under Fire as a passive-perception/reactive-dodge type move.
E.g.,
PC: "So I take another swing at the Chopper..."
Me: "Wait, roll to do it under fire."
PC: "Uh, ok, why...?"
Me: "Roll and find out."
PC: "Sure, that's, um, a... 9."
Me: "So, you catch movement out of the corner of your eye: this guy is going to bash you in the back of the head with bottle. You can suffer that damage, OR you can block him but then take -1 on your punching."
PC: "Shite. I'll risk the -1."
Me: "OK, you deflect the incoming blow at the last minute. Now Sieze By Force, but at -1..."
etc.
-- 77IM