INFO VISUALIZATION: Stories about a redesigned New York subway map have been floating around (notably Gothamist and Jason's Notes).
I actually like both for different reasons. The redesign (left) sacrifices having a consistent scale for the benefit of showing clearer curves as well as showing the multiple lines sharing a single tunnel. If I had to choose one for my own use, I would choose the redesign simply because it mimics my own conceptual understanding (model) of the trains.
Of course, you can take abstraction way too far with maps. Just check out the subway map from 1972:
But, that's just my opinion. Check out the current official subway map, a few small pictures of this redesign, a redesign by Michael Calcagno, or Dynamap (which is very cool but only includes Lower Manhattan).
My personal favorite? A redeisgn by Joseph Brennan. His map includes NJ connections (like Path) as well as other light rail connections around the city (like the JFK Airtrain) and really gives you a good understanding of the entire region.