  Non-Fermi liquid behavior is shown to occur in two-dimensional metals which
are close to a charge ordering transition driven by the Coulomb repulsion. A
linear temperature dependence of the scattering rate together with an increase
of the electron effective mass occur above T*, a temperature scale much smaller
than the Fermi temperature. It is shown that the anomalous temperature
dependence of the optical conductivity of the quasi-two-dimensional organic
metal alpha-(BEDT-TTF)2MHg(SCN)4, with M=NH4 and Rb, above T*=50-100 K, agrees
qualitatively with our predictions for the electronic properties of nearly
charge ordered two-dimensional metals.
