Commit co-authors makes it easy to see who has contributed to every commit, regardless of how many contributors there are—and every author gets attribution in the pull request and in their contribution graph.
Gitweet is a convenient tool for developers and makers that wants to quickly tweet something about their last code update. Once your repository is linked to a twitter account, every time you provide a description in a commit (completely optional obviously), a tweet will be posted with the provided content. Only the description will be tweeted.