As you probably know there are entire web sites dedicated to this very subject. But assuming you have looked at our favorites at http://www.roadtripamerica.com/links/destinations.htm

I would have to nominate the Bandy Haven Trolls (Sequim, WA) -- for some photos check out http://www.roadtripamerica.com/places/bandys.htm

And for performance art -- The Houdini Museum in Scranton, PA is pretty odd -- But fun! http://www.roadtripamerica.com/places/houdini.htm