Justine Rosenthal has an interesting article in the current issue of The American Interest called Business Bombs: The Rise of Terrorism for Profit (abstract only).
The article is about the tendency of terrorist organisations to show an increasing profit motive when their ideological calling is diminishing in impact - or in some cases to be primarily motivated by the profit factor.
Witness the growing involvement of the Abu Sayyef of the Philippines, the FARC of Colombia and the Islamic Movement of Uzbekistan in the drug trades after their respective revolutionary causes took a decline in popularity or urgency.
Of course, for many of these organisations, the possiblity of profit often leads to thje drug trade. This site has covered several issues of such organisations profiting from drugs.
It is also interesting to note that the largest geographical areas of drug production harbour a lot of such groups in and around the same areas.
The article is well worth a read and if you get a chance, The American Interest isn’t a bad publication either.