1. This might mean bulk or consolidator tickets, or sometimes broken fares and/or multiple tickets/PNRs that can cause trouble if you miss a "connection" or even want to check a bag through to your destination.

2. The big thread listing and reviewing these award booking services (which apparently don't violate rules except that some FF programs prohibit giving control of your account to another person).

3. These would be the mileage brokers. They can leave you stranded far from home with no return ticket.