My favorite drug, caffeine. Check out this article from ABC Science Online.
A quote: "Associate Professor Pradeep Nathan of Monash University, an expert in behavioural neuroscience who was not involved in the research, says caffeine stimulates the central nervous system including the brain, where it affects several neurotransmitters.
The Melbourne-based researcher says it improves memory and makes us pay closer attention to tasks at hand.
"It does improve attention and it can improve memory so by being more attentive and remembering your attitude to a particular thing may change," he says."