No one is quite sure what kind of particles neutrinos really are. They cannot be directly observed. Their presence can only be inferred because of a failure in book-keeping of conserved quantities (like charge, spin, and momentum) in all of the other observable particles in a given reaction. Currently accepted theories assume the mass of the neutrino is zero, and that it acts similar to a photon in how it transports momentum and energy, but in addition, it also has spin. Some experiments which have tried to determine the mass of the neutrino have come up with a negitive number for its mass squared (the quantity which could be inferred from the experiment) which would suggest that the neutrino has an imaginary rest mass. If this is true, then it may be possible that neutrinos are actually tachyons (tachyons are particles which can only travel faster than light, luxons (ie. photons) can only travel at the speed of light, and bradyons (ie. normal matter) can only travel at less than the speed of light).

Since the event horizon of a black hole is defined as the location in the gravity well of a massive object where the escape velocity becomes greater than the speed of light, then it may be possible that neutrinos could still pass through the event horizon. Although, I am unsure how the gravity well would affect the motion of the particle since it would not be possible to slow it to the speed of light.

Anyway, this is my interpretation of Dr. Forward's discussion of neutrinos. I hope I got at least somewhat close to what might be considered the truth.
What do you think about neutrinos?Do they have mass or not?
And how small they are 10^-35m or lesser?
How much do we know about neutrinos?

From the Newtonian standpoint, only particles with mass can be subject to a gravitational force. From the Einsteinian standpoint (General Relativity), however, gravity is the warping of spacetime due to the presence of a massive object. This gravitational force, as we experience it, is the three-dimensional projection of a four-dimensional (spatial dimensions) phenomenon. Impossible to visualize, but pretty cool. Anyway, all of spacetime (and everything it contains) is affected. So, even photons and neutrinos are at the mercy of gravity.
NOTHING can pass through a black hole and emerge on the other side. The event horizon is effectively a boundary between OUR spacetime (everything we can observe) and THEIR spacetime (whatever freaky things go on near the black hole's singularity, assuming it exists - but that's another discussion altogether). No information can pass from within the event horizon to without it, as the escape velocity at the event horizon is equal to the velocity of light. This includes particles.
Black holes, however, CAN be seen. Vacuums aren't empty, as we've all been led to believe. Heisenberg's Uncertainty Principle has all sorts of weird implications. Among them is the fact that empty space is crawling with "virtual" particles - particle-antiparticle pairs that instantly annihilate, releasing their energy in the form of photons. The energy used to create these virtual particles is "borrowed" from the vacuum. When they annihilate, the energy is "returned." Near the surface of a black hole, however, there are massive tidal forces (differences in the strength of gravity). If the tidal forces are sufficiently powerful to overcome the attraction between the virtual particle pairs, then one particle may be sucked into the black hole, while the other roams free. Their mass-energy had to have come from somewhere (it hasn't been returned to the vacuum). It turns out that the black hole is the source. This radiation is called Hawking Radiation, after the great Stephen Hawking.

Any opinions?

"They cannot be directly observed" Not true - there are experiments (Katmandu) which observe them.

"Currently accepted theories assume the mass of the neutrino is zero" Not true - above experiments lead to a small non-zero (not too well known) mass. There are 3 kinds of neutrinos and they have different masses.

" Some experiments which have tried to determine the mass of the neutrino have come up with a negitive number for its mass squared " The experiments don't give the mass squared, but rather the differences between mass squared of the different neutrino species.

I didn't see any point in reading further.

Actually they are NOT directly observed Mathman. They are observed as a result of a neutrino's collision with a substance in which light is given off and detected.

You're right, but is it worth quibbling about? Are any subatomic particles directly observed? We only infer them from their interactions. For example cloud chambers show a bunch of water vapor trails, from which we infer properites and identities of various charged particles.

nutrinos travel slower than the speed of light -- they have rest mass, its about 20eV

Not much slower. And despite having a little mass, they scarcely interact with other matter at all. Although the odd one does collide with a particle in a sealed detector and produce light which we can observe, the majority of incident neutrinos pour effortlessly through the whole Earth like light through through clear air. According to Arthur C. Clarke, they could theoretically pass through a wall of lead billions of kilometres thick.

Which is why Solar neutrino flux can give accurate indications of conditions in the heart of the Sun. The neutrinos pass from their point of origin to Earth in only a few minutes, whereas photons take thousands of years of radiative transfer to work their way up from the Sun's core to its photosphere, and into free space.

Oh, and the 3 types of neutrinos are paired with the three types of lepton: electron neutrinos, muon neutrinos, and tau neutrinos (the heaviest variety).