I like the staples - they all have their role to play in pushing the brain where you want it to go. Caffeine enhances concentration - my understanding is that continual small does (e.g. drink tea all day) are better than one big hit.

Alcohol mitigates biases against socially acceptable ideas by reducing inhibition. Think spirited debate over a pint, not all night bender. I find I am more receptive to odd ideas after a couple of beers.

THC (the main active agent in marijuana) is good for flashes of inspiration. I find my software designs when baked are brilliantly out of the box (the code itself usually needs a cleanup the next day). A downside is that it can affect short term memory, which reduces your ability to perform mental accounting. Best for working on large sheets of paper or whiteboards, during the planning/design phase of a project. The brain seems to adapt to it - smoke every day and you just think you're more inspired...