I have a few friends who are into H. P. Lovecraft [1] and a few others who are into trains. This HO scale model of the city of Arkham [2] should appeal to both sets of friends (link via Flutterby [3]).
[1] http://www.hplovecraft.com/
[2] http://www.ottgallery.com/WelcometoArkham.html