I would love to have the option to send an email/notification to all admins/selected admins of all or selected child sites.
That way, I could easily update admins of eg new wp releases, new PHP updates and plugin updates - and ask them to be aware/or check their website for issues related to the various updates.
This is something that you can accomplish with Pro Reports or Client Reports extension. I know these extensions are not really designed for this, but it’s easy to use them for this.
For example, if you take Client Reports, you can just write up your notification (even just one and use your custom tokns for name, url,…) without of actual report tokens and your clients get email with your announcement.
For the Pro Reports, it’s the same, you just need to create a custom template.