My most unique handgun would have to be my RPM Merrill Pistol wide frame in 45/70 Govt. This gun is one of six prototype pistols made with a stainless steel frame. All of the other RPM frames were plated in hard chrome. More pictures and info. are in my article on RPM pistols.

http://www.handgunhunt.com/photopost/data/807/4-Wide_Frame_Prototype_45-70_Govt_.JPG