Exit Strategy NYC is an iPhone app that tells you where to get on the subway train so as to be in an optimal position when you get off.
Taking the 1 train uptown to 28th street? Get on right behind the middle conductor. Need to transfer to the L at Union Square from the N downtown? Ride in the 1st car. Detailed diagrams eliminate the guesswork and frustration from your ride, making your subway trip easier and faster.
Update: The Times writes 650+ words on an app that calculates prewalking coordinates but doesn’t use the word “prewalking”.
Update: Exit Strategy NYC has been updated to include every stop in the subway system and subway entry points.