What are some examples of non-Lambertian light scatters/radiators in everyday life? What are some examples of non-Lambertian light scatters/radiators in everyday life? How to easily demonstrate their difference from Lambertian ones?
 A: Most surfaces are going to be non-Lambertian to some degree. My desk is a good example. There are multiple scattering from the rough wood surface producing Lambertian scattering but there is also specular reflection from the varnished top layer of wood. 
Lambertian scattering depends on the surface having a sufficiently random level of roughness. Once you start reducing the roughness or randomness you will get non-Lambertian diffuse scattering. There will be a directional component to amount of scattering so by tilting the surface you will be able to detect it. The peak scattering angle will depend on the degree of roughness but it will be at the same angle of the specular reflection for only slight roughness. A rough sheet of metal would be one example of this scattering (and also the varnish layer on my desk, it hasn't been polished for a long time so it will be full of micro-scratches).
A: How much scatter do you need?   Mirrors and corner-cube reflectors are certainly non-Lambertian.   Any number of machined surfaces with designed roughness or structure are non-Lambertian, e.g.  reflection gratings.
Beyond that, if you Google for "BRDF" (bidirectional reflectance distribution function) you can probably track down any number of homogeneous materials whose angular reflectance is not perfectly Lambertian.
See, for one example, http://rads.physics.miami.edu/optics/ken/OtherPapers/A22_MSZV_OOXV_2000.pdf 
