Dazzleman: do you know where there's detailed (by borough and lower if possible) results of NY Mayoral and etc elections?
I remember reading detailed results on the elections, to the precinct level within the boroughs, in the NY Times. So you could try the NY Times archives, but I don't know if stuff that's more than a year or so old is available online.
Another source could be either the New York City Board of Elections, or the board of elections at the state level.
If you know the racial and ethnic composition of New York City neighborhoods, as I generally do, it was striking in the past few elections to see the racial divisions show up in the voting numbers, with huge differences in voting among adjacent communities depending upon the predominant race of the residents.