Flickr started as a side project from a high concept online game that was really an excuse to socialize and collect things. The photo thing took and the Flickr guys were smart enough to cultivate a success when they found it, but games still pop up inside Flickr from time to time. like this one. Flickr Gold lets you give out gold medals after you get one, Flickr Poker and High Five let you hand out several awards a day and accrue kudos to photos with lots of awards. Sort of a carebear version of an old Flickr game, deleteme.
These games seem a bit silly, but I think people really like this kind of tokenization. It's not enough to say "this photo is good", the ritual of collection and the structure of game rules makes it seem more significant for people.