In order, North to South...
Main Line NHB (Boston to New Haven)
Main Line MS (Mill River to Springfield)
160.9200 FMN - Road
160.5150 FMN - MOW (aka: Production Channel)
MNCW New Haven Division (New Haven to New Rochelle)
160.5450 FMN - Road
New York Connecting Track (New Rochelle to Sunnyside)
New York Terminal District (Sunnyside to Penn Station 'A')
Main Line NYP (Penn Station 'A' Interlocking to Philadelphia Zoo Interlocking)
160.0100 FMN - Road
160.6500 FMN - Sunnyside Yard / Phildelphia Station Services
160.4250 FMN - Philadelphia Car Department
160.5150 FMN - MOW (aka: Production Channel)
Main Line PW (Philadelphia to Washington)
160.9200 FMN - Road
160.4400 FMN - Washington Car Department/Services
160.5150 FMN - MOW (aka: Production Channel)
And as MTACOP noted Amtrak Police use 161.2950 FMN divisionwide, with the PL depending on what repeater they're using.
The only places you may not hear much is between New Haven and Boston, as well as New Rochelle and Penn.
West of Penn you'll hear plenty due to the density of up to 550 trains per day between Penn and Rahway when you factor in 4 NJTransit routes in various segments. To the South, it's between Wilmington and Baltimore you'll hear the most due to a decent amount of freight traffic. People will try to tell you NS only runs freight at night, and it's not true. The curfew was permanently lifted earlier this year. If CETC can fit it between passenger, they run it.
