The current contribution can be seen as a sequel of the Springer books "Occultations for Probing Atmosphere and Climate," edited by G. Kirchengast, U. Foelsche, and A.K. Steiner, published in 2004, and "Atmosphere and Climate - Studies by Occultation Methods," edited by U. Foelsche, G. Kirchengast, and A.K. Steiner. While these books contained scientific results presented at the 1st and 2nd OPAC workshop in Graz (Sep 2002, Sep 2004), the current contribution features new results, presented at the 3rd OPAC workshop in Graz (Sep 2007), in the form of peer-reviewed papers.