I made myself a FlagFox action which submits the current URL to Google Charts and makes a QR code out of it. Easy enough.

...and what happens to any private repos when it's over?

I tried to find information about this on their site for half an hour the other day, couldn't find a thing.

I would hope that they would stay private, and that you simply wouldn't be able to push any new commits to them.

They become read-only (and still private) and you get a big ol' red box at the top of every Github page asking you to pay them or downgrade to the free plan. (http://cl.ly/0W3X0g1l0N13450b0C00)