What websites, publications or real estate professionals would you recommend to people looking for rentals in Greenwich Village, New York City?

Start with Craigslist under the "no fee" or "by owner" sections to try to avoid paying a broker fee. Sadly, it's pretty hard to do so if you don't see anything, go under "all apartments" and try to work with a broker on additional no fees. You may end up having to pay them which most people do. They charge 10% of a year's rent. The vacancy in New York right now is under 1% so the brokers are hard to get around. You can also go to a brokerage's direct site where they have all of their listings. The biggest ones in NY are Bond and Citihabitats.