The relative ease to measure quasar redshifts together with their luminosities higher than galaxies, and their low intrinsic space density, make of them interesting candidates to map mass(galaxy) concentrations in the Universe. Given that it is widely accepted that quasars are fueled by accretion of gas into supermasive blackholes (SMBHs) in the nuclei of host galaxies, the recent observations of galactic centers suggesting that many galaxies have SMBHs with masses correlating with the luminosities of the spheroids of their host galaxies, has significantly strenghtened the potential use of quasars as mass signposts.
Using a new technique that allows better determination of the boundaries and redshifts of galaxy clusters from multicolor sky surveys, it is shown that quasars with z .LT. 0.3 do trace well the galaxy LSS at corresponding redshifts. The location of the quasars within a given galaxy LSS is found to be non- random, which in turn allows to understand the variety of quasar environments reported in the literature and gives clues about the relative dominance of competing quasar formation mechanisms. If this behaviour would prove to apply also at higher redshifts, it may explain the well establish result that higher-z quasars cluster on lenght scales smaller that 10 Megaparsecs.