[leethargo]

I have a free GitHub account and also have GitHub Pages for my blog, which is developed in one of my public repos.

Do you mean some specific additional features for GitHub Pages, such as a vanity URL, or building from private repos?

[d2p]

Just private repos. When you look at the GH pages section it says "Make this repo public to enable GH Pages" or something. Your existing site still serves, but it doesn't build anymore.

[metahost]

Building from private repos did not work for me once I downgraded to the free tier.