Just off the top of my head: Joe Louis Sugar Ray Robinson Ike Williams Jose Napoles Alexis Arguello Julio Cesar Chavez Mike Tyson Evander Holyfield Ricardo Lopez Roy Jones Jr. Marco Antonio Barrera Juan Manuel Marquez
Interesting that it seems no one mentioned Ali!? ALi vs Cleveland WIlliams may be the greatest example of throwing fast on-target combos ever seen!
Corrie Sanders. Much better than anyone else I've seen. Tyson's most deadly weapon was his missed hooks. RJJ's , McCallum's and others' flurries barely hurt their opponents but rather brought the referee into a ready to stop the fight mode . Sanders' combinations were probably the cleanest and the best.
Flo Raiden beat me to Ike Williams. Him, Ray Robinson and Joe Louis all threw combinations with great balance and excellent technique. I like El Finito's combinations as well.
Sugar Ray Robinson & Joe Louis. This guy deserves a mention: [ame]http://www.youtube.com/watch?v=Hv7zyil9QwQ[/ame]