  We discuss the variation of cosmological upper bounds on $M_\nu$, the sum of
the neutrino masses, with the choice of data sets included in the analysis,
pointing out a few oddities not easily seen when all data sets are combined.
For example, the effect of applying different priors varies significantly
depending on whether we use the power spectrum from the 2dFGRS or SDSS galaxy
survey. A conservative neutrino mass limit of $M_\nu < 1.43$eV (95%C.L.) is
obtained by combining the WMAP 3 year data with the cluster mass function
measured by weak gravitational lensing. This limit has the virtue of not making
any assumptions about the bias of luminous matter with respect to the dark
matter, and is in this sense (and this sense only) bias-free.
