I just spent a good half hour calling up EVERY Japanese 
restaurant listed in the phone book for my area of Manhattan.

Was that fun? I don't want to go there if that's the case... Feh...
distinct lack of Japanese resturants for such a large city! Melbourne
has a Japanese resturant or two on almost ever block in the city! :p

Only ONE of them serves okonomiyaki, and THAT'S on special
order (they don't actually have it on the menu). Is there
any particular reason why this is so hard to find? From
the way it's talked about in Ranma 1/2, I had the impression
that it was a rather common food...

Well, there's one resturant in the city here that serves real okonomiyaki,
the others serve the crappy cabbage squares that they call okonomiyaki.
Maybe not every resturant has a griddle to cook the okonomiyaki on...
Though you can find okonomiyaki batter mixture in the Japanese department
store in the city...

Kun-chan...