Rockmover wrasse (Novaculichthys taeniourus (phew!)).
For my money, the juvenile versions of these (see, for instance, this guy) are pretty much the niftiest looking fish on the reef. K. called this fish "saucy" and given the way it was flipping around back and forth trying, almost showing off for the camera -- I can't say I disagree.
Kealakekua Bay, November 2009.