So when was the moment that you really shined, or the one that got your heart racing? I'm sure that everyone who has played a tank has had those great moments...
For me, I was playing my warrior in EQ and my guild was raiding the plane of fire. We were killing general reparm and things started very badly... something happened with the CH chain and our first three tanks (the only ones specified in the lineup) went down within seconds. There was only me and a new recruit left.
I smacked my defensive discipline, hit taunt and my AE taunt, and the fun began. If you've ever tanked this guy, you know what I mean... basically he hit for up to 3k damage (4 attacks per round) and had a nasty proc (was a couple K damage, I forget now). When you're a fighter with only 9500 HPs... well, it gets exciting, even with the defensive disc cutting down on his normal attack damage.
With the AE taunt and a couple quick procs from my weapons, I got aggro locked and was watching the damage and heals flow in. It was just incredible. I slowly moved him into the right position and was watching his health start dropping (my own health was going up and down like a yo-yo). The other tanks in the guild were cheering me on in tank chat and I had so much adrenaline running through me that I probably could have picked up a VW bug
Reparm finally got me with a quad attack that landed all 4 swings and a proc on top of it, but for about 45 seconds it was one of the most intense gaming experiences I've ever had. Our last warrior stepped in after I dropped (Reparm was nearly dead by then) and held him for the remaining few seconds of the fight.
I don't know if it's really possible to describe the experience... but I remember it like it was yesterday. Fun stuff.