I agree, I'm unsure of what the hook is for someone to download the mobile app and use it. Perhaps it would make sense if human.io came as a framework developers could import in their existing apps?

With this, they could potentially send out notifications to just their audience when participation would be useful. Completing tasks could also be a micropayment allowing the developer to give the user some sort of reward (like unlocking bonus features).

This is exactly correct. We expect publishers to talk about the task to be done and the motivation for doing so as the primary thing (and the fact that it happens to run on the human.io client or in a browser or whatever as secondary.)

I think there are going to be different kinds of users and different kinds of task publishers. Each will utilize different motivations around what they do. We are working on a way to allow this. I think that payments are good, but there's also coupons/offers, gamification or social standing, participatory privilege, etc.

I worry that if we do micropayments for microtasks we'll end up in a very specific pigeonhole that isn't insanely interesting.