Path Schedule provides a pretty straightforward interface for determining the next PATH train. If you don't live/work in NYC or NJ this may be less useful for you...
Path Schedule shows all trains that will travel through a given station today and tomorrow, as well as the last 3 trains for either eastbound or westbound trains. You can swipe between PATH stations or tap the station name to pick from a list of stations.
Path Schedule shows holidays schedules, however there's no way to handle schedule changes that are not part of the released schedule data from PATH.
I wrote this because I had become frustrated by other apps that relied on the destination, rather than just the point of origin. I live in New Jersey around Grove Street, and usually I can take either the 33rd or WTC trains regardless of where I’m going in Manhattan – most apps will show you a particular route, but I wanted to know all trains moving through Grove Street toward the city.