All these people that say "if the healer or dps pull extra mobs, I let them die" need to get off their high horse and do their job. You're not special because you are the tank. If I'm pulling small and the healer picks up another group, instead of acting like a 5 year old throwing a temper, I just pick up the adds. I'm then happy at that point that i'm probably playing with confident players who know what they can handle and I pick up the pace.

Now if they can't handle it when they do pick them up, that is another story. However, you need to DO YOUR JOB and find that out first before throwing your little tantrum.