I am working for a US regional Airline.
Employee, spouse and parents fly for free without any extra charges within the US. You will be charged taxes for international travel as a non rev PAX. The same rules basically applies to the Major Airline who's name we are flying for, except that we have a lower boarding priority.
Jump seat for pilots are for free with 90% of all 121 carriers in the US. (I believe that more than 50% of all airline pilots in the US commute to work)
We have international jump seat agreement with most other US airlines. You do have to pay taxes for international jump seating flying back in to the US. (It is usually no fees or taxes flying out from the US) I have also been lucky to get the jump seat within the EU on full flights, but only after surrendering my ZED ticket.
We have ZED agreement with other ZED carriers. The cost is only based on a zone system. A round trip two legs tp Europe is about 150-250 USD with taxes.
I believe most US 121 carries have somewhat similar travel benefits.