Ok, I'll kick it off this week. This is a plot from Shen et al (2008, arXiv:0810.4144) who study the correlation of QSOs in the sky using the SDSS DR5. They look how clustering depends on luminosity, black hole mass, colour and radio loudness. What they find is perhaps a bit surprising but not entirely new - there is virtually no dependence on any of these parameters, except radio loudness. So - don't go around expecting a QSO to necessarily live in a massive halo, at least not at z<2.5