Mediamatic presents a two-day workshop on social tagging or Mobtagging. Mobtagging is what happens when groups of users freely apply labels (metadata) to online information. This allows road users to specify, index, search and share information on their own terms and conditions. This practice has become popular on sites such as Flickr, Del.icio.us and Technorati and is developing into an important alternative to centrally organised information structures on the web.