I know that others have the same sentiments. For instance pictured above is the hat of one of my good friends in game. She's had those moose antlers for about 2 ½ years from Onyxia. I know that she'll never get rid of them, and if she did... well, our guild would probably have to gdisband.
There's something nostalgic about keeping around old gear. It provides a memory of "the good old days" when hitting 60 actually meant something. Those old pieces of gear meant that you had accomplished something epic when epics weren't free. Our old epic pieces of gear are a testament to a time when the game was still new and the wilds of Azeroth were really wild.
I might be waxing a bit too philosophical here, but for some reason I still like to look at old screenshots of my characters and muse about the times we had. A piece or two of the gear only brings back those memories, and only good things. And that gear will never be going away.
What pieces of gear are you keeping around forever and ever?