MTA Trip Planner
The New York City Metropolitan Transit Authority (MTA) has produced a text based trip planner interface that allows you to navigate between locations in New York City, forms of travel that it will take into consideration are bus, subway and walking - you can fine tune how much walking that you can do.
NYRoute has a nifty NYC Subway route planner that uses google (They call it an interactive transit map) that allows you to click on the start and destination on the google map and it figures out the best route using the New York Subway system.
Its another system that's not entirely accurate - so you have to take the information with a pinch of salt.
Uses a handy address to address route planner to guide you thru the New York Subway system.
Much like a satellite navigator, but you need to take the directions with a grain of salt.