I decided Lehr's comment on instant replay being unnecessary, and that you should suck it up when calls go against you, was worthy of a full post.
The only people who can sincerely disagree with replay are a) people who don't care about the outcomes of games, and b) people who have never watched in awe as someone makes the dumbest call in history against their team. Alex spoke the truth when he acknowledged he hadn't had any bad calls go against him. The only team of Alex's that hasn't won it all in his lifetime is the Knicks, and they've been the beneficiary of lousy calls far more often than the victim. (Hue Hollins, anyone?) Few things are worse, as a sports fan, than to watch your team actually win, but have the game taken away by a blown call. Compound that with your team being the underdog, or the opponent being your hated archnemeses, or going for a prolonged period without having won a championship, or all three at once, and you start to get why it's important enough not to simply chalk stuff up to human error and move on.
The only time I can think of that replay has led to the wrong outcome is the infamous Snow Game. That's the only game-related argument against instant replay. But honestly, the Raiders won an identical playoff game from us in 1976 in what I understand was a far more specious call (not the enforcement of a BS rule, but a roughing-the-passer penalty that never happened). The Pats actually WERE the best team in the AFC that year. So fuck the Raiders.
Every sport should have video replay. Football and hockey have good systems in place, and the NBA and NCAA are starting to get the picture, so really the only slackers are MLB (no surprise there). The NFL's system is nearly ideal, where coaches have two challenges per game, and two successful challenges results in a third. It's a good system, but if I were King Of The World, I'd make it so you get two wrong
challenges per game. If you were right, you shouldn't be penalized for a goddamn thing. I would extend existing replay rules in hockey and basketball to be more like the NFL's, where coaches request replay instead of having the refs decide. I can understand opposition to that; it's a little like having the patient tell the doctor what drug to prescribe. But you have to assume that the doctor (or ref) is a total quack whose first cousin, once removed, is Brick Tamland. Trusting coaches to use challenges judiciously and responsibly may not always be the best policy, but it's much worse to get the call wrong and have no way to reverse it.
Baseball, given that so many rules exist, is the one sport that demands replay the most, and whose game quality would suffer the least from a stoppage in play. Baseball is like 70% stoppages in play anyway, so why haggle over five more minutes if it means you get the calls right? At a minimum, baseball needs to enact video replay on any play other than balls-and-strikes (Don't Go There!) that causes a difference between an out or a run. That covers pretty much anything that someone would be pissed about. They don't have that big-ass rule book for nothing... anything can be fixed.
Speaking of balls and strikes, I would also propose, as King Of The World, approval of The Nuclear Option. Typically, judgment calls like fouls, balls and strikes, and penalties are not reviewable, because there are too many variables in the equation. Most of those variables have to do with not showing up the oh-so-sensitive officials, but I can see why the leagues won't touch it. (Don't Go There!) The problem is that judgment calls get blown a lot more frequently than reviewable calls do, and they cause just as much damage if not more. The Nuclear Option gets around that. Once every game, a team can review absolutely positively MFing anything the referee calls. If you're right, you get to use it again later in the game. If the refs don't overturn the call, you lose your Nuclear Option for a few games (ten for baseball, five for basketball/hockey, three for football) pending league review (if the ref really was wrong, you get your N.O. back). That way the coaches look stupid if they use it without justification, but they also have protection from the league's governing bodies in case the ref was ruling irresponsibly.
This will never happen, because it takes away the ability of major pro sports leagues to fix games. (Don't Go There!)