Couldn't resist doing this off clickflashwhirr's exquisite photoset: www.flickr.com/photos/clickflashwhirr/sets/72157626172514...
Part of the research into visualising/digitalising memories for my graduation piece Aleph.
Code's really basic, I'm simply counting the individual rgb values for each pixel and for each portrait, and dividing those values by the number of portraits (update: 500+ at this time).
UPDATE: As www.thisiscolossal.com requested a slightly larger version (thanks for blogging btw!), I took that chance to update the picture to the current size of clickflashwhirr's collection that was available in hires: slightly over 500.