No matter what, the cops have to harass SOMEONE. Other groups the NYPD has been directed to issue summonses to and arrest, in no particular order:
Passing between subway cars.
Taking photographs within the subway system.
Appearing and actually being intoxicated.
Bringing your bike into the car without knowing the rules, in the manner of a douchebag.
Hopping the turn style (Though, even I've done this, and still do on occasion / when drunk and can not find my metrocard)
Please feel free to add your own offenses and personal stories in the comments