Users of information systems, for example the WWW, are confronted with ever growing amounts of information and thus often feel overwhelmed with data. In this work the author shows that the metaphor of Trails, which are a record from other users browsing paths and activities, allow, users to navigate vast information spaces more easily. He examines the search behaviour and the navigation methods of professional office and knowledge workers in the personal information space, i.e. the WWW and corporate directories. Based on this analysis a common trail model, a trail similarity measure and a trail recommendation method, a selective procedure for finding similar users with similar trails and the recommendation of documents, are introduced. The trail model is integrated in an open software framework, which supports the generation, manipulation and querying of trails by any application. The framework supports arbitrary clients and allows for variable algorithms to be plugged in for providing recommendations. The integration possibilities of different application types are shown by sample applications including a Browser Manager, a Print Manager and a Desktop Manager.