Graduated neutral Density filters are used to take landscape photographs and bring bright sky to land's dynamic range. The one I got is not very expensive as they can be. :) Still, it was very high dynamic range at sunset the filter can't handle. I guess it did some good job, but not a miracle.
Anyway, here are some pictures. Today when I was editing them in Lr5, I realised that I should have shoot at f/11 or wider instead of f/18 as I did.