Disappointinly few. In terms of full unification fights, I can only think of Leonard-Hearns 1. Partial unifications? Carbajal-Gonzalez 1 for the WBC/IBF light flyweight title Chavez-Taylor 1 for the WBC/IBF light welterweight title
Calzaghe-Kessler was almost full unification. The WBA, WBC, and WBO titles were on the line. Calzaghe relinquished the IBF belt he took from Lacy. Pretty good fight, not great. Hopkins-De La Hoya was for all 4 titles. Oscar had the WBO belt after that gift against Sturm. That fight wasn't all too good.
Yeah, like you say, Calzaghe-Kessler was a good fight rather than a great one. Hopkins-DLH was technically a full unification but the reality was Oscar was a challenger to Hopkins' championship. The real unification was Hopkins-Trinidad in 2001. And of course, both featured high quality performances from Hopkins but weren't great fights.
Carbajal-Gonzalez. At least I think it was a unification match. Carbajal was IBF and Chiquita was WBC.
Whilst this one technically doesn't count, WBA middleweight champion faced IBF middleweight champion James Toney in what should have been a unification bout in 1991. Instead, the WBA stripped McCallum of his title ahead of the fight for not defending his strap against his mandatory challenger, Steve Collins, who he'd already convincingly beaten the previous year in defence of the very same belt! Another bonkers decision by the WBA which was 100% about the money: "The WBA wanted $30,000 from McCallum's purse, plus a $35,000 exception fee for letting him fight Toney," said Milton Chwasky, McCallum's attorney. "We were going to go along with that. Then they came back and demanded we give Barney Eastwood, Collins's manager, another $50,000 for stepping aside. That's when we said no." So the fight was just for the IBF title and the ended in a draw, meaning McCallum ended up with no titles... but at least he retained his dignity. Oh yeah, and the fight was fantastic as well.
More of a steamrolling than a great fight, but Joe Frazier - Jimmy Ellis I comes to mind. It did feature Howard Cosell screaming, "Down goes Ellis! Down goes Ellis! Down goes Ellis!" three years before Foreman - Frazier's iconic call. Frazier - Ali I was sort of a unification, depending on your point of view.
