What sort of generic adventures do you think the crew of a free trader could get involved in that didn't have anything to do with buying and selling according to the trade system?
A few off the top of my head, some of which I've used:
- Passenger problems. (Sabotage. Noisily needy guests with exotic and damaging pets that get loose while in jump. Mad scientists doing experiments in their cabin. Undercover assassin. A wealthy passenger with expensive cargo, except the cargo gets damaged in transit. A pregnant passenger goes into labor. etc.)
- Making contacts. (In order to win the favor of a buyer/broker, you have to do them a little favor...)
- The Cargo Is Not What It Seems. (Something breaks out of a freight container. The "food cans" are really illegal drugs. Radioactive waste. Stolen weapons.)
- Engine Trouble. (Ship breaks down somewhere remote. Have to find parts, fuel, etc. )
- Red Tape. (The ship is impounded for improper paperwork. Players must negotiate a confusing bureaucracy to get it released, which may also require illegal dealings.)
- Distress Call/Salvage. (Hey, we've got a few extra tons of cargo space, let's check out that derelict over there...)
- Moral Choices. (The broker offers a sweet deal for huge profit. The cargo? Slaves. (Or pharmaceuticals from a company that uses exploitive/unethical test subjects. Or severely endangered animals. Etc.)
There are a lot of possibilities.