Heidelberg Project -- a great DIY folk art surreal outdoor junk sculpture: http://en.wikipedia.org/wiki/Heidelberg_Project
Fisher Building -- The Tower Peanuts Built. The lobby is like a secular art deco temple to capitalism. A peak Detroit experience was visiting Bill Van Loo's office, and going out onto a little balustrade many stories up. I was scared to death, and it was irresistable... http://en.wikipedia.org/wiki/Fisher_Building A ride along the River Rouge on Jefferson -- start about at East Grand on Woodward and promenade west past the RenCen and out to River Rouge (the town) or Ecorse... a depopulated urban wasteland west of downtown. Melodies and Memories -- Submerge is a great place to shop for techno, but Melodies and Memories has a ton of stuff all over the stylistic map. Record Time -- My favorite store was in Hamtramck because it's on a nice little High Street, but I think it's closed, and only the Ferndale and Roseville stores remain. Oh, and Google Street view has photographed much of Detroit!