  We present different classes of initial data to the three-dimensional,
incompressible Navier-Stokes equations, which generate a global in time, unique
solution though they may be arbitrarily large in the end-point function space
in which a fixed-point argument may be used to solve the equation locally in
time. The main feature of these initial data is an anisotropic distribution of
their frequencies. One of those classes is taken from previous papers by two of
the authors and collaborators, and another one is new.
