For me, it depends on the situation. I remember my screenshot of our first Kimigola kill in SWG where we posed side by side in front of its open mouth. Other times its just something that strikes me, flying my dune ships in front of a planet, the scene of a chaotic hours long battle in Planetside or just my character standing somewhere that makes me think "I've got to get a picture of this". I still have them, safely tucked away in my hard drive.

That said though, I hardly seem to use it anymore. The places I run across just don't inspire me to stop and take a shot to remember it by. Maybe it was because I was younger and MMO's where relatively new to me so I wanted to capture those moments in time. Now, in many of the games I'm in, it seems all to familiar whether its my first time logging in or my 100th.