Neutrinos as Dark Matter

I've discussed neutrinos before, way back in June, but we can also look at neutrinos as a form of dark matter. As previously mentioned, neutrinos are highly non-interactive as it would take a block of lead an eighth of a light-year wide to stop just one neutrino. However, they are abundant as they are a product of the fusion going on in the cores of stars.
We also know that neutrinos come in six different flavors, depending on the associated lepton (electron, positron, muon, anti-muon, tau particle, and anti-tau particle) and that when they interact, they can change flavors.
But remember, that neutrinos have virtually no mass, though they are not massless. Since there are so many stars and have been billions of stars in our own galaxy creating neutrinos every time fusion occurs, there must be a lot of neutrinos existing in our galaxy, as well as other galaxies. A lot of something that has little mass ends up having a huge mass. Therefore neutrinos are probably another component of dark matter.
Again, the hard part to confirm that neutrinos make up dark matter is (1) that they are nearly massless, so any gravity they impart is small, and (2) they virtually do not react with matter. So although there is a lot of neutrinos out there, they are hard to detect.