Pilots at airlines (121 carriers) get jumpseat benefits on other carriers. In addition most airlines have decent travel benefits (non-rev) for immediate family members (spouse/significant other, kids, parents).
Most are free travel on your own airline, significantly reduced travel on any immediate affiliates (IE United for United Express guys), and reduced benefits on other carriers ($15 one way to 90% off a full fare ticket and everything in between).
Travel and jumpseat benefits are definately something that makes the airline world distinct from other careers, and something that I definately miss now that I'm out in the corporate world. It really sucks having to pay for airfare when I used to fly to Europe for less than $50 round trip.