In Markdown, it’d sure be swell if GitHub rendered items that normally @autocomplete across the site. Example, I wanted to attribute a user (or anything with a github.com/github.io URL for that matter), like so:
[@Schacon](https://github.com/schacon): [GitHub Flow](http://scottchacon.com/2011/08/31/github-flow.html)
It would then render in Markdown on GitHub as: