An interface allowing people to find many others who are lookalikes (or nearly lookalikes) of themselves, and then enable them to compare notes with each other re: possible shared tendencies/tastebuds/etc. It could enable people to upload images of themselves whereupon a 'Face Recognition Bot' would guide them in dragging their JPEG to an area of other JPEGs most closely matching their image in an array.
A numeric equivalent to such an array is:
11 12 22 23 33 34 44
45 55 56 66 67 77 78
This was inspired by Nancy Segal's book about twins separated at birth - Entwined Lives
Discussion
Related Ideas