Internally, my company uses Yammer as its social network. When I went to a company-sponsored tech conference last summer, they suggested that we use a particular hashtag for all of our posts. Since we had people literally flying in from around the world to attend the conference, I thought it would be cool to build an app which showed the posts which included the suggested hashtag as a highlighted where everyone was from.
For a full description on this project, please see the full article.