  We consider the quasiparticle c-axis conductivity in highly anisotropic
layered compounds in the presence of the magnetic field parallel to the layers.
We show that at low temperatures the quasiparticle interlayer conductivity
depends strongly on the orientation of the in-plane magnetic field if the
excitation gap has nodes on the Fermi surface. Thus measurements of the
angle-dependent c-axis (out-of-plane) magnetoresistance, as a function of the
orientation of the magnetic field in the layers, provide information on the
momentum dependence of the superconducting gap (or pseudogap) on the Fermi
surface. Clean and highly anisotropic layered superconductors seem to be the
best candidates for probing the existence and location of the nodes on the
Fermi surface.
