Because I was bored and looking for something fun to do, and because I'm a nerd that thinks "fun" is using dice roll generators to plot the probability curve of sci-fi cargo, I have modified my original 2d10 cargo curve.
The NEW version:
3. raw materials: ore, lumber, plastics, chemicals
4. manufactured goods and textiles
5. simple electrical/mechanical parts
6. advanced/assembled electronics and machines
7. robotics and cybernetics
8. polymers and synthetics
9. medical supplies: diagnostics, vitamins, vaccines
10. foodstuffs: seeds, spices, alcohol, preservatives
11. petrochemicals, fuel cells, propellant
12. weapons, ammunition, explosives
13. precious metals and silicates
14. radioactive materials/waste
15. luxury items
16. exotic items
17. stolen items
18. illegal weapons and modifications
19. illegal drugs, chemicals, exotics
20. human cargo: slaves, wetware, corpses
I changed the layout specifically based on what I thought would be the most likely cargo - fuel.
Then to either side of that I arranged medicine, food, weapons, and precious metals. I think that about covers it for the five most common things you'd find in a ships hold.
I figured the least likely things would be livestock and human cargo (not the paying passenger type).
If you can't tell, I had Firefly in mind quite a bit when I crafted this.
And in saving the best for last, I recently came across this Star Citizen: MISC Freelancer video.