[nate_meurer]

One possibility: big financial institutions. Michael Rupert has done a lot of work in this area. IIRC, the illicit drug trade is the world's largest commodity market -- bigger than oil. That money has to go somewhere, and wherever it goes it is bound to be massively influential. Rupert argues that the links to big financial institutions are often quite clear, and he backs up his arguments with fairly prodigious research.

[phaedon]

Not just a possibility. Wachovia/Wells Fargo helped Mexican drug cartels launder money. Here's an article from back in April about it:

http://www.guardian.co.uk/world/2011/apr/03/us-bank-mexico-d...