Commercial organization that serves as a go-between to allow criminals to find work. Employs heavy public key encryption. Illegal on all civilized worlds, but you find them everywhere even so.
Omertas are not criminal organizations, but organizations of criminals. Someone whom wishes to hire a criminal will send an encrypted message requesting a crime to an omerta. Using public-key encryption, not even the omerta will know who hired them. The omerta will then send someone who can do the crime -- note, not even the omerta knows who they're hiring, again public key encryption. The criminal hired never knows who hired them, they just do the job. The result is crimes that are impossible to trace to their source. And through digital cash it can be made completely untraceable.
Using special protocols some criminals (both freelancers and groups like the Ronin Guild, Assassins for Hire, Cybercat Burglary Inc. and others), post advertisements and lists of "achievements", linked through layers of cryptography so that it is impossible for anyone to trace them back to the criminal but it still works as identification.