The Mexican Mafia has significant operational control only within prisons, yet manages to tax street gangs at rates of 10-30% of revenues. It has become a kind of government. A PDF of the corresponding journal article exists here.
Saving Mexico "To weaken the cartels, some argue the U.S. should legalize marijuana, let cocaine pass through the Caribbean and take the profit motive out of the drug trade."
"Police in Mexico are investigating claims that rival drug gangs are using the internet as a new battle ground."