Drupal is an open-source content management system, which means there are thousands of developers around the world working together on it, but not in any one physical location. One way to bring together a diverse community like this is through conventions where members physically get together, like Drupalcon. And one way to make events like this make more of a long-term impact is to have branded items that people can take home with them. One way in which Drupalcon really leveraged the event and the product online was to have a contest to design the official Drupalcon t-shirt. Rather than have the conference organizers create a design, they essentially used the open source model for their own promotional products.