I've been meaning to try out Github Pages for quite a while, but never had a project that was suitable as nearly all of my work is built on a custom back end server. I also wanted to get a few old projects online to share the code so people can maybe do something cool with it.
My favorite part of the system is how it's simply and orphan branch inside of your standard git repository, which you would already be hosting there anyway. No extra management or uploads to update the repo, simply commit to the gh-pages branch. Another great advantage is that it's away from your standard infrastructure and keeps the source code and demos all in one place for your project.
A great way I've seen people using this is to host their Blog using Octopress. Since you compile the entire locally into static html files, it can be stored in a git repo and served directly out of the repository. Demo pages are also popping up everywhere, which is quite interesting to see them hosted in the same place as the source code itself meaning they are often updated at the same time, and the horrible days outdated demo pages are being more rare.
This post is in no way a Tutorial or Guide, but simply here to highlight that Github Pages exists and that you should try it out if you haven't already. I currently use the manual deploy method which you can find here. Hope someone finds this helpful and has an awesome use for Github Pages.