  The Numerical Renormalization Group is used to solve quantum impurity
problems, which describe magnetic impurities in metals, nanodevices, and
correlated materials within DMFT. Here we present a simple generalization of
the Wilson Chain, which improves the scaling of computational cost with the
number of channels/bands, bringing new problems within reach. The method is
applied to calculate the t-matrix of the three-channel Kondo model at T=0,
which shows universal crossovers near non-Fermi liquid critical points. A
non-integrable three-impurity problem with three bands is also studied,
revealing a rich phase diagram and novel screening/overscreening mechanisms.
