High-energy emission from galaxies is the footprint of AGN activity. Surveys at hard X-ray energies (above 15 keV) have turned out to be a powerful tool for detecting AGNs in the local universe (z < 0.4). Despite extensive studies, this source population is poorly understood. One of the main reasons for this is the low sensitivity due to instrumental noise that characterizes these surveys. Here we show that it is possible to boost the sensitivity of current surveys at hard X-rays by merging the surveys of Swift and INTEGRAL. As a result statistical and systematic noise is minimized. The Swift - INTEGRAL X-ray (SIX) survey is the most sensitive survey right below the energy range of Fermi-LAT. We present evolution studies of AGNs in this energy range and we show results on the circum-nuclear environment of the super-massive black-holes at the center of AGNs. Predictions of the recently launched NuSTAR mission are presented as well. Furthermore, we show possible applications of the SIX survey for associating Fermi-LAT unidentified sources in the Galactic Center.