I just ran across this: Flickr member information on
camera usage (and pretty graphs too!). This is a great use of
the wisdom of crowds. Since digital cameras embed information about
themselves into photos (called exif - check a
sample exif here), when photos are uploaded to Flickr (or
anywhere else), Flickr can quickly find out who used what camera
for any given photo (if the camera supports exif, of course). If
you happen to use a mobile phone (like my example above) and your
mobile phone has GPS, the camera can even put information in about
where the picture was taken. Automatic geotagging.
Another neat use of exif: since it has the date information, it can
be used to automatically rename photo files. Picasa (Google's photo
organizer) will actually do this for you - select a bunch of files,
select rename (keyboard: F2) and along with naming there are a few
checkboxes for "rename by date." Link: http://www.flickr.com/cameras/