I already suggested it somewhere in TMO but here is again:

- Location field in the profile (supporting different options, in order to deal with privacy)
- Devices field in the profile (770,n810,..)
- Type of member field (developer, power user, user)

Then this information can create a nice map with different colors for each type of member, something like these ones:

http://www.valeriovalerio.org/images/ubuntu_map.jpg
http://www.frappr.com/ubuntu/map
http://pear.php.net/map/