blocks administer content management

I'm sure many of us have noticed a need for better block management. Or at least, these people have:
http://drupal.org/node/343710, http://drupal.org/node/416002, http://drupal.org/node/197844, http://drupal.org/node/386532

It does get harder to keep the blocks in the right order and to find the one you want to edit as the list grows, but my biggest problem is handling visibility settings.

As a user, here's how I'd expect to use blocks: