What is my best WoW Memory? That's a tough question since I have done so much. With 10 85s, I've seen just about everything except Ragnaros H25 (and then some!).
I can fondly recall a Kara run with some lower level guildies. It was me at level 80 along with our raid healer, Teetsman. Sadly her toon is not online anymore, but I assume she'll be back eventually. We one shotted everything, with absolutely no one dying. The best part was Prince Malchezaar though. When I charged and started to tank him against the wall, the random number god struck, dropping an inferno right on us. All lowbies died instantly.
I had to move Prince 5-6 times as he was hell bent on wiping Teets and I. Prot warriors at level 80 didn't do the fantastic DPS they do today (even with gear inflation taken into account). Needless to say, 9 minutes later, Prince fell to my blade (and a few flame shocks from Teets) and we looted!
I'd say the floor on the top of the tower was about 60% covered by infernos. I've repped out with 5 toons so far and am still working the rest though mount farming. This WoW memory would be easily replaced if the mount dropped. I've only seen it once :(