I've always liked geography, or maybe more accurately, geostatistics (although I love travel, too, and would probably score higher than most Americans on a geography test. I'd still get crushed by Swedish schoolchildren who ride the "short bus", though, probably.)

I took a couple of classes in the geography department in college.

Whilst surfing for maps (jackpot: http://www.citimaps.com/manhattanmaps/full_manhattan.PDF), I found these maps of census data that break down the population of NYC and then map it according to various categories including race, income and ethnic origin. They're fascinating.

Check out the New York City 2000 White Population, and dig the line-of-demarcation on the east side at about 104th street. I can just imagine the radio stations in the taxis spontaneously changing from Classic Rock KPLJ to Hot 97 as they drive up 2nd ave.