Blackmail Iguana Bob

This quest actually starts in Junktown. Go to Doc Morbid's Hospital and climb down the ladder. You'll meet a mentally-challenged short guy named Gretch who'll let slip that he's sorting out some human body parts to send to Iguana Bob in the Hub. If you confront Doc Morbid over it, nothing will happen and you can't tell the authorities. If you kill Gretch, the Doctor and his bodyguards will attack, but no one else will be that bothered.

Go to the Hub and find Iguana Bob's stall Downtown. You'll need a high speech skill to frighten him enough. Depending on your Barter skill, you can blackmail him for a large slice of his profits and then come back when you have a higher barter skill to renegotiate. Be warned though, he does have a cut-off point that will turn him hostile if you try and make him pay it.