You are very welcome to add it for your own website, but this is not a feature that we would like to add to the system :) it should be a relatively easy form to put in though and you can likely copy most of the existing admin implementation and add a few security steps like activation and/or admin approval.
It's also worth noting that you probably don't want to give them the standard administration roles that users get added to them when added through the admin interface, depending on what you're trying to do..
You are very welcome to add it for your own website, but this is not a feature that we would like to add to the system :) it should be a relatively easy form to put in though and you can likely copy most of the existing admin implementation and add a few security steps like activation and/or admin approval.
It's also worth noting that you probably don't want to give them the standard administration roles that users get added to them when added through the admin interface, depending on what you're trying to do..