Following a link from the FlickrBlog lead me to the most excellent flickr game I have ever played. Basically it shows you a photo from one of your Flickr contacts and presents you with 3 choices - you pick who’s photo you think it is. I seem to be doing quite well at the moment - it seems most of my contacts have quite distinctive styles.
Congratulations once again to FD for some awesome uses of the Flickr API.