There's a paper on drought stress written by Dr. Deron Caplan.
As I understand it he grew a bunch of plants and subjected them to different levels of drought stress.
The short version is, if you allow the plant to dry back to a certain point in flower it will produce 10-20% more cannabinoids than identical plants (clones from the same mother) grown under identical controlled conditions minus the drought stress.
He even identified a means of determining whether or not the drought had gone on long enough.
The whole thing is covered in the droughting thread Krissi started.
It only applies to soil, not any form of hydro, and I'm not sure how well it works with organics, especially since it involves letting your soil dry out.
Edit: There's a link to the paper in the droughting thread, but I'm not digging to find it. That thread got huge.