As a herder, I find it best if I first ask the team if they want head on or herding. If they would like a little herding action I tell them where I'm planning to herd to(I love dumpster diving dreck, or the little corner the middle of dom) then kindly ask them to stay out of sight until I ready in, I'll usually ready in, wait for the first person to attack, then I footstomp to reaffirm my aggro.
One odd thing is that even if it seems you lost aggro on a mob, if you kill your current followers quickly the ones going back home will all of a sudden come after you again. Here's an example: I was on a team with two SS tanks(one inv/ss, one fire/ss), a kin/dark def, and two fillers that were outside. The two tiered room in the back of bobcat mish right before you open the door where bobcat is, easily had 50-60 baddies in it. I ran around the room and angered all the mobs and tried my best to kept a really tight group of massive proportions. When one mob would break off and start to return I would hop over and hand clap or footstomp them, then jump back in my original pack and knockout blow one of them(great punchvoke) and keep the pulling going. I finally got to my herding spot and readied in. With a nice fulcrum shift, some tenebrous tentavcles, and a few foot stomps that mob was history, next thing we know there's another pack coming around the corner and we quickly dealt with those out only to have a third group come in. When the battle was over I went back to see what was left and there were 3 single stragglers scattered about, otherwise it was pretty much an entire room pull. Granted I miss the taunting capabilities of yesteryear, but this worked quite well.
To me, my job is to keep the squishies alive and let them do their job, I could have used a good tank many times during my defender's career. Even when pulling a single mob, I like to keep them close to me so I can manage aggro to the best of my abilities. I'm also here to absorb the alpha strike, and to make sure any heroes that get a little ornery and wander off aren't annihilated. Grouping/Herding/Corner pulling are a great aspect of tanking to me, it makes cone attacks and AoEs more effective, it makes the healers job easier when all of the baddies are in one place and heroes aren't scattered everywhere fighting their own battles, and it helps a tank do his job.
