Most tanks are control freaks. As a matter of fact, you should hope that your tank is a control freak, because the ones who shrug off a mob running around loose are the ones you probably don't want tanking your run anyway. With that in mind, there are several player abilities that, while great for soloing or PvP, don't make the transition to a 5-man very well. Either they make life a real nuisance for your group members due to inherent design, or they tend to do so in the hands of a player who doesn't deploy them in a particularly helpful fashion.
Not all tanks will have the same degree of irritation with all of the following skills (for example, I play a druid, and because bears don't have a ranged silence, a knockback on a caster mob is much more likely to annoy me than, say, a death knight tank), but I promise you that they've all been mentioned by my tanking colleagues as abilities with a high chance of blowing a pull.
Thunderstorm, Typhoon, and Blast Wave
Some of you may recall that I have written on the subject of knockbacks before. I wasn't really fond of them in 5-mans then, and I'm not really fond of them now.
When they're awesome: If you're knocking something toward a tank, knocking a loose mob away from the healer, or you're a boomkin and Typhoon is the only way you have to interrupt, say, the Ghostly Priest's heal in heroic Halls of Reflection, then a knockback can be at least be helpful. I'm not going to lie and say that the annoyance factor will vanish, but I will grudgingly concede that you're using it for a good reason.
Why tanks hate them: I don't build aggro on stuff I can't hit. Beyond that, the number of players who stop and think about the results of blowing caster or ranged mobs away from a tank is vanishingly small. If I've line-of-sighted a pull and dragged the mobs into a narrow area, it's because I want them in that specific position, and line-of-sight is the only way I have to force them to come into tankable range. If you knock them away from me, a ranged mob is going to stand wherever you just put them and keep trying to kill me, and I can't silence casters to force them to mosey on over. My only silence is also a stun, which doesn't help the positioning issue. While other tanks can deal with caster mobs a little more easily than bears can, there's no guarantee that their interrupt is off cooldown or that they'll be able to silence multiple enemies to get them to move again.
The bottom line is that, even deployed correctly, knockbacks play havoc with where the tank actually wants the mobs.
Divine Storm and Bladestorm
When they're awesome: At any point after I've had the chance to beat on the mobs for longer than 1-2 seconds.
Why tanks hate them: Because that never happens.
Army of the Dead
When it's awesome: Did the healer disconnect? Is this phase 2 or 3 of the Black Knight in Trial of the Champion or...well, pretty much at any point in heroic HoR's trash waves? Is a pull going to hell, I'm about to die, and the healer's out of commission? Not only is that a great time for AotD, but I'll also thank you afterwards for having the foresight to pop it in these circumstances.
Why tanks hate it: On any boss or mob with a frontal cone attack, cleave, or tail swipe, AotD is usually more trouble than it's worth. The enemy will just keep spinning around to target and stomp ghouls on all sides of them, which means that the mob is basically uncontrollable for as long as the ghouls are still up. On any boss encounter or trash pull where the mobs being uncontrollable is a highly undesirable occurrence, please rethink pulling out the little beasties. Healers will also hate you for popping Army on, say, Keristrasza and getting them tail-swiped out of the party's range.
Why it's awesome: Because it exists.
Why tanks hate it: Because Murphy's Law dictates that the people who actually need to use it are the ones who don't seem to have it hotkeyed.
When it's awesome: There are a lot of places in Wrath dungeons where it is not particularly convenient (or sometimes even possible) to line-of-sight a pull. If you Death Grip a caster or ranged mob over to the group for me -- say, an Ahn'kahar Spell Flinger charging up a Shadow Blast -- I will be your bestest buddy for the rest of the run.
Why tanks hate it: The odds of your running across a DPS death knight who uses Death Grip correctly seems to occur at a rate of around 1%. Far more common is the DPS DK who impatiently pulls the next group before you do, but lacks the sense to at least pull a caster mob while doing it. The inevitable result is a melee enemy beating on the death knight while I run around like a giant idiot trying to grab aggro on the rest of the pull while taunting a caster who refuses to move.
When it's good: Did I miss an enemy or get stunned straight off the pull? Is some nasty little mob running for the group and I'm gouged/stunned/feared/silenced and unable to taunt? Pop it under those circumstances and you're gold. Did you Frost Nova a runner? Thank you. No, seriously.
Why tanks hate it: From a tank's perspective, Frost Nova is much like knockbacks in that it plays havoc with positioning. For the period where the mobs are completely rooted, there is nothing we can do to position or reposition the pull in order to avoid damage or respond to a nearby patrol. It's also not unusual for a Frost Nova'd pull to have multiple enemies scattered just out of melee range of each other, with me in the middle desperately trying to convince all of them to hate me more than you while you're charging up a giant Blizzard or Flamestrike. The rest of the DPS, seeing you unload, has started doing the exact same thing. I blew Challenging Roar the last time you pulled that stunt, and it ain't up now. Good luck!
Worst of all is a mage who pulls aggro and then panics and frost novas the mob/s. Not only is the pull now likely to be split between two groups of mobs, but a rooted mob will instantly aggro whoever's next to them regardless of threat, and that's a great way to get someone who wasn't doing anything wrong killed.
Any ability that allows you to hit a mob right after I've pulled it but before it reaches me
When it's awesome: Pretty much never, unless you are a hunter pulling something into a trap.
Why tanks hate it: The moment I see a DPS hack/shoot/cast at a mob while the pull is still on its way over, I know I'm in for a long run. Not every mob pack is positioned in a way that makes it possible for me to charge in and build threat without aggroing more packs, in which case I will stand at range and pull it. I will have a limited amount of threat on the mob on whom I slapped a Feral Faerie Fire, but on everything else, the only thing that makes them hate me more than you is the fact that I just made their buddy mad. If you so much as sneeze in their direction, they will immediately turn your way and try to kill you. While I know it's annoying to wait 2-3 seconds while the pull runs my way before you start DPS, I die a little inside when the pull is a disorganized mess and not a neatly-arranged little clump in a spot that's convenient for everyone and easily AoE'd in the event that AoE is possible.
Behavior like this makes me not want to PUG as a tank through the Dungeon Finder. Please -- help me help you!