Kottke.org posts about a very cool site that has a hypertext map of Manhatten called New York Songlines.

To this end I offer these as the New York Songlines. An oral cultures uses songs as the most efficient way to remember and transmit large amounts of information; the Web is our technological society's closest equivalent. Each Songline will follow a single pathway, whether it goes by one name or several; the streets I plan to follow from river to river, while the avenues will at least at first be read only in part, focusing on the upper Downtown/lower Midtown part of the island I know best.

I browsed through a few of these and was impressed at the work that had gone into it. Parts of it were a little confusing, but the detail was really interesting. The cool thing would be to find a way to load this into a PDA when you went to go do the tourist thing.