Habitable planets in different stellar environments

Habitability in Different Milky Way Stellar Environments: a Stellar Interaction Dynamical Approach
http://arxiv.org/abs/1306.0464

Considers the effects of stellar flybys in the solar neighbourhood, the Sun's birth cluster, open clusters and in particular the old open cluster M67, the globular cluster M13 and the galactic bulge/bar.

According to this, M67 looks like it could be an interesting environment to search for potentially-habitable planets. The outer regions of globular clusters may also be dynamically favourable for planets, provided they can form in such low-metallicity environments. The inner 1kpc of the galaxy does not look like a very nice place to be.