It's a first-world problem that can take a lot of time. I'd much rather go to a single site and send out all of my invites than navigate to four individual sites and muck about in the settings to send an invite.
Another thing that would be awesome if your could get even finer grained control of some of the services. Like having the ability to maintain some additional Github permissions. A big pain point for us right now is you need to have admin to manage teams, webhooks, etc. Have some levels between admin and write would be great (and I don't blame GH for having these. It's a more enterprise need.)