I've even managed to save quite a few older ones from when I started playing. I know for a fact there are about a year's worth of screenshots I lost moving from my laptop to my desktop PC about four years ago, which makes me a little sad.
As nice as my memories are of some of the things I have done in game, I do like to have a visual prompt to emphasise said memory.
Some of these screenshots are of my characters before having race/faction/name changes:
This one is the hunter I recently transferred to Draenor, as she originally started. I had made her for the Classy Humans achievement in the guild achieves. Yes, that is indeed Sambas I had tamed earlier that day!
I also found a shot of Aurorasofia with Loque'Nahak:
I also found out that taking too many Potion of Illusion created an interesting graphical but on my then human Paladin:
I even have kept screenshots from characters I don't even have anymore:
I have killshots from Heroic Hagara:
Yet apparently didn't keep the shots from the other Heroic bosses we downed in Dragon Soul, though I do have this shot from preparing for Warmaster Blackhorn:
I think we definitely needed more guild chests!
I have one screenshot from our Elegon kill:
I have screenshots of random events in game that I still don't know why its there:
Screenshots that were just begging to be taken:
And occasionally I like to just sit and take a picture of the view: