This paper describes the experience of introducing a service for semantic bookmarking and search in the Earth Observation (EO) domain. To perform the work reported such a service has been integrated and customized in the framework of the DILIGENT project which concluded in 2007. The service proposed is a web browser ontology based extension: at the application layer the interaction between DILIGENT end-users and this service takes place from within the DILIGENT web portal. The service described allows end users to capture and annotate on-demand the information stored in the DILIGENT infrastructure and to organize it according to the user's representation of the specific ontological domain. The effort spent meets today end users' requirements in the EO application domain, applying an innovative solution to make specific actors keep track of the information of interest in a personalized and easy way. End users are able to store, access and play only with the information of inte...