Limits on Neutrino Masses from Large-Scale Structure
  Massive neutrinos have a detectable effect on cosmological structure formation, in particular on the large-scale distribution of galaxies. Adding Hot Dark Matter to the now-standard Lambda CDM model leads to a worse fit to large-scale structure and CMB anisotropy data. This results in a limit on the mass of the most massive neutrino of 4 eV, assuming a power-law primordial power spectrum. 
Eric Gawiser (U.C. San Diego)