*** Updated January 2014 ***
I've done a bit of a re-vamp of the cage sizes comparison, just limiting it to the main 20 cages available at the moment.
The data I've collected is: name, dimensions, type (wired/tank/part wired), main materials, bar spacing (if available), if any shelves are included, and a rough price range at the time.
I've calculated a crude floor space in square centimetres (just by multiplying the outside measurements of the width and depth, allowing for a 1cm difference), but this does not include any shelf space or any other space available (i.e tubes).
This is not a definitive list of cages, as there may be some I've missed off, or some information may differ slightly between websites (ive gathered info from a few different websites).
The graph below shows the cages in order, by my calculated (approximate) floor space, and thought this might be interesting to other members.
Hope these are useful