The Art Deco lines of this BMW, actually designed in the 20's and 30's could be passed as something new and modern:
1930's BMW - My favorite from a design standpoint. This bike's production run was never begun due to the war. The only surviving unit was found in a box and restored in 2007.
My favorite, flat track inspired Harley with Husqvarna tank:
Confederate Motors gets the industrial design nod for the following bikes:
Victory's CORE Concept is another good one:
And my favorite future concept is the hubless bike