Here are some examples of where I was able to do just that. It's tiny things, but it feels great to make something better.

https://github.com/liveprogramming/2013/pull/1/files

https://github.com/liveprogramming/2013/pull/2/files

https://github.com/skx/bookmarks.public/pull/1/files

https://github.com/gittip/www.gittip.com/pull/625/files

https://github.com/mojombo/semver.org/pull/55/files