Github seems to be down.
Edit: After I made this, their status page finally updated to indicate an issue.
Update - We are experiencing interruptions in multiple public GitHub services. We suspect the impact is due to a database infrastructure related change that we are working on rolling back.
https://git.30p87.de with 90% uptime (I reboot the server 10% of the time due to bleeding-edge arch testing kernel updates)
Oh, I run my own Gogs server internally, but for collaboration, we all use Github.