Somehow, I come to associate particular icons more strongly with the people behind them than others. For qos, for example, the icon of the woman holding the sword is it, quintessentially her. For shusu, it's her red one. Both of these people have various other icons, but those are the ones I most strongly associate with those two people.
Does anyone else experience this phenomenon? Do you have favorites among your friends' icons, and do you miss them when they're gone and wish you'd copied the graphic?