Drugs are certainly interesting, especially in this country. But nootripcs have been around for thousands of years, in herbal medicine from China, India, south america, everywhere actually. Most, if not all tonic herbs will increase focus. The "tonic" herbs are the ones which Taoists revered for immortality, and believed them to greatly strengthen the body. Similarly to building muscles up stronger by going to the gym, tonic herbs strengthen the organs, the governers of bodily functions. But the good thing about herbs is that they balance the body's internal states of energy as well, keeping the organism healthy, which most people do not care about since we are looking for quick and easy ways to do things. Well there are immediate boosts in mental clarity from natural substances, people just don't know...here are some great options that will help people study better. And for the herbs, I recommend buying the actual herb and making a decoction/tea out of it, it's cheaper and more potent in many cases. Most of these herbs are also known as adaptogenic herbs too

1. Cacao beans/nibs - contains phenethylamine, closely related to methamphetamine, also high amount of antioxidants, blood flow to brain, keeps me up all night, too stimulating actually. Contains L-DOPA, domamine, serotonin as well... very complex
2. Cacao powder - cheaper, less effective, but pretty good boost
3. Rhodiola rosea - I have two articles on this on therawhigh.blogspot.com if you want scientific studies, stimulates CNS, not necessarily good for us who always stimulate the CNS. (i'm not selling it in the website)
4. Fasting in the morning, intermittently -increases brain levels of acetyl-l-carnitine
5. Anxiolytics - sedatives in other words can relax the brain, promote alpha brain waves, better than being overdriven in beta brainwaves for memorization.
6. Ashwaghanda - aphrodisiac for men and women, usually recommended for men. Helps resolve issues with HPA axis, helped me recover from overtraining like nothing else ever did.
7. Turmeric - obviously good for brain, and joints, inflammation. Kinda stimulating tho
8. Schizandra berries - less stimulating, feel it in brain pretty fast to sometimes.
9. Reishi mushroom - revered in china, calms the body
10. Meditation: I don't know the mechanisms really, except the alpha brainwave thing. Yogis who practice Kriya Yoga, a very meditative form, have told me they can retain almost everything they read. They are in a different state of conscoiusness, definitely more alpha brainwaves.
11. Hemp seeds - pretty damn cheap on nutsonline.com ($3/lb). One of the most potent plant based omega-3 forms, usually you can "feel" the brain energy right away. Chia seeds are even more powerful but difficult to chew. Good plant protein source too, and proteins are also good for the brain.
12. Marshmallow root and slippery elm bark - some recommendations to balance out the body. Many of us here on this forum need Yin yonics, b/c jumping and high intensity activities deplete the body. These have helped me focus, even tho it doesn't really make sense how.
13. BEEF LIVER - just so full of minerals . . .
14. SPIRULINA - also a food recommendation, contains 40+ trace minerals, gamma-linoleic acid, it is about 60% amino acids itself, pretty damn good brain boosting supplement and protein, and detoxification.