What's the best travel guide for New York City?

For a short visit, 3 or 4 nights. Can be an online source or published.

a taxi driver.

this is not exactly a travel guide. it's more of a plan. it will get you into many places for a cheap price.
http://citypass.com/

an open mind :-)

Not to be flip, but whichever one suits your personality and preferences.

Some people want to hit all the tourist spots, some people what to do museums, or shop, or visit ethnic areas, so there are guide books for all of them

Might I recomend going to your local library, Dewey Decimal system section 917.471
and look at tour guides. (It's free). When you find one, you like, buy yourself a copy.

Myself, I like walking tours so I recommend looking at "The Big Onion Guide to New York City: Ten Historic Tours" (see Amazon link below)

For a published guide, I like the Knopf CityMap Guide because it is a small 4'x6' book that can easily travel the city with you. It has a brief listing of attractions, restaurants, bars, and shopping, but what makes it invaluable on your visit are the fold-out neighborhood maps as well as maps of subway lines and bus routes

Soundwalk CDs are also fun, but a bit "off the beaten path".

See below for some other websites of some fun things to do in NYC....

I have generally found Fodor's guides to be excellent.

http://www.fodors.com/miniguides/mgresults.cfm?destination=new_york_city@111

You would also be wise to invest in a small, foldable map (including subway stops) that you can easily carry with you and refer to.