How can I aggregate information from about 30 Drupal sites in one place?
The Similar Module Review's Administration module wiki lists several options.

The following show some usage statistics, as well as Drupal core and module updates:


Droptor (Requires paid service for more than 1 site.)
Drupal Remote Dashboard
Network Manager (Drupal 7 version doesn't exist yet.)
Sentry Server (Drupal 7 version doesn't exist yet.)