For a few years, I’ve been thinking of putting together a single webpage that would allow admins to see the health of their site from one place. This dashboard would contain stats showing the vital aspects of any site and would give a quick glance at how things are going.​​
It’s now live and the dashboard provides an up-to-date glimpse into your site’s activity and data. Metrics are available on logins, registrations, updates, administrators, email blasts and more.

You can see all the profiles that have admin access. You can tell when other admins last logged in. You can see stats on your last email blasts.
The dashboard is accessible from both the homepage and the Admin page.