The GroupMe! system provides a novel approach to social bookmarking. It enables users to create groups of arbitrary multimedia web resources and visualizes resources according to their media type. Therewith, content of a resource can be grasped immediately. Hence, GroupMe! groups form web sites -- comparable to Wikipedia pages -- that users visit in order to gather information about corresponding topics. Technically, the grouping of resources carries valuable information about web resources and their relations, and can be exploited to improve the mining of web content, e.g. for search and retrieval. GroupMe! is available via http://groupme.org.