Hmm, let's see...

Current:
Ricky Hatton cuts it pretty good to the body
Jeff Lacy's hooks are like Frazier's in that they're short, compact and powerful
Cotto has good hooks and knows how to work the body.
Jose Luis Castillo times his perfectly on the inside, very accurate and powerful.
Barrera goes without saying.

All Time:
Julio Cesar Chavez' left hook to the body makes me cringe just thinking about it.
Joe Frazier is a given.
Floyd Patterson's leaping left hook was beautiful.
Trinidad's left hook was amazing it was just telegraphed.
Sugar Ray Robinson had a very good hook. It's underrated because he used to put them together in flurries rather then just landing them as one big punch.