GitHub Pages, aka. free hosting for all your public demos:

Without your writing any webserver code, GitHub can recognize specifically-named repos/branches and will serve a static page (including HTML/CSS/JS and other static files) at a certain GitHub-based URL. This means free hosting for your public demos, and makes it really easy to host a doc/demo site associated with each of your repositories. You can even set it up with a custom domain.

User Page (or Organization)

• Accessible at: yourusername.github.io
• GitHub automatically reserves this URL for every user and organization to use as their User page, although nothing is published there until you publish.
• To deploy a static site to this URL:
  1. Create a Github repo with the exact name: yourusername.github.io
  2. Commit an index.html in the root folder to the master branch and push. (From the index page you can link to other folders/files as usual)
  3. Visit yourusername.github.io - tada!

Project Page (for a repo)

• Has content from any repo that is owned by you - not only what lives in your User page repo
• Accessible at: yourusername.github.io/your-other-repo/
• To deploy a static site to this URL:
  1. Create a branch in your your-other-repo repo named gh-pages.
  2. Commit an index.html in the root folder to this gh-pages branch and push.
  3. Visit yourusername.github.io/your-other-repo/

You can make your GitHub Pages site more powerful/organized by taking advantage of the static site generator (Jekyll) that GitHub will run your page through by default, but it is optional. If you haven't included any Jekyll-specific configuration, it will be served exactly as-is.

https://help.github.com/categories/github-pages-basics/

If you want to start making use of Jekyll to take advantage of some conveniences that would normally be handled by a website backend, I recommend this guide:

http://jmcglone.com/guides/github-pages/

http://jekyllrb.com/