I have two huge favorites.
One was in Unrest when me and two buddies were farming for his necro's epic loot drop (Cannot remember what it was). Either way, Unrest didn't have a lot of people in it at that time. LOIO seemed to be the more popular camping spots. We had the zone to ourselves, so my buddy pulled the entire house down to Rucksif's room. If you remember that layout, you would watch the puller come down from the top, down to the right, jump over a small crevice, and then they were in the main room where Rucksif spawned. Well... We were overpowereds for the zone but it wasn't too crazy. Mid low 50's, but the Necro 49 pet was amazingly OP'd at the time. So I parked him at the front of the room, my buddy Dextor (Went by Kaubel over in EJ) was a druid and had all his AoE shit ready... and down came my other buddy.
"Um...."
He had that entire fucking zone behind him. As he was running for dear life down that stairwell and over the crevice, I started laughing uncontrollably when I saw all the undead flailing NPC's mindlessly running behind him not stopping. It was so funny. I laughed for 4 minutes. I couldn't even hit a button to cast a spell, I had tears in my eyes. My Pet was going nuts, Dextor was haviung a heart attack with his AE's, Wolvinsbane was going nuts trying to get aggro off.
7 minutes later everything was dead in a heaping mess. Including Wolvinsbane. And my pet. But somehow Dex and I survived. And out of all that, I think he needed a batwinig or something and we wanted a little extra drama to spice up the search, he didn't even get it. SO we went out and just killed a few bats and that took care of that.
Another was a 7 hour stint in the Emp Crypt in Sebilis. Zurren from Afterlife was our puller, the guy was awesome... Supa was with us. We just had a fantastic group and they were really good players obviously. So I just was content watching this oiled machine bring in the XP for 7 hours straight. And when Zurren pulled, that guy pulled. He must have pulled half that place to our little group.