With more than 17 million photos, Flickr is becoming more and more interesting. We use their Zeitgeist to post clinical images in the sidebar of this website.
If you wand to get a free Flickr stikr (stickers, that is), send a self addressed envelope to:
Sunnyvale, CA 94088
Other cool stuff on Flickr:
My childhood, seen by Google Maps
Zoto.com - the next Flickr?