I really don't mean to be a jerk, but this sounds like a terrible idea. Four places to send invites from? That's a first world problem, not a startup business opportunity.
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.
We have 100s of developers using Github, HipChat. This service would be quite useful. Especially the offboarding.
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.)
Your use of "then" rather than "than" makes it read like you do two steps in a specific order rather than the, I assume, intent of using a better alternative for a time consuming process.
Since when were first world problems not startup opportunities? It certainly doesn't sound like the next Google, but it could be a good side project that pays for his next vacation.
I've been involved at a few startups that over a year later my accounts still are not disabled. At one I logged in six months later and disabled myself.