  We discuss three different scenarios recently proposed to account for the
non-Fermi liquid behavior near antiferromagnetic (AFM) quantum critical points
in heavy-Fermion systems: (i) scattering of Fermi liquid quasiparticles by
strong spin fluctuations near the spin-density-wave instability, (ii) the
breakdown of the Kondo effect due to the competition with the RKKY interaction,
and (iii) the formation of magnetic regions due to rare configurations of the
disorder. Here we focus on the first scenario and show that it explains in some
detail the anomalous temperature dependence of the resistivity observed e.g. in
CePd_2Si_2, CeNi_2Ge_2 or CeIn_3. The interplay of strongly anisotropic
scattering due to critical spin-fluctuations and weak isotropic impurity
scattering leads to a regime with a resistivity rho = rho_0 +Delta rho(T),
Delta rho(T) =T^{3/2} f(T/rho_0) \propto T sqrt{rho_0} for sufficiently large T
and small rho_0.
