Around 2000, the Department of Transportation installed distinctive black and white signs developed by the Alliance for Downtown Manhattan that featured easy-to-read street names, house numbers found on the block where the sign was installed, and a stylized representation of a local landmark. The signs went from the Battery up to about Fulton Street. After the Twin Towers of the World Trade Center were destroyed by terrorists, the signs showing them were permitted to remain.
The Alliance has also installed information kiosks featuring maps, local highlights, and historical buildings.
These are the best street signs to ever appear in NYC and I wish they could have been used as a template for signs all over the five boroughs.