Adderall, Caffeine, Aniracetam, ALCAR, Ginkgo Biloba, Choline, Vinpocetine and a high quality EFA blend. That stack has been money for me for a while now. I have to watch the Ginkgo though... For whatever reason it raises my B.P. even more than the Adderall, though its' benefits outweigh that side-effect I.M.O.
P.A. mentioned fasting... I've found taking a break from everything but the EFA blend is very helpful in avoiding tolerance buildup (though taking a day off from caffeine can be a real bee-otch of a headache).
D-Serine looks very interesing and I'm thinking of giving that a try soon. I'd also like to try a new racetam... I hated Noopet (the anxiety it caused offset any benefits) and I've been taking Aniracetam for a while now. Any reccomendations? Phenylpiracetam looks interesting but is expensive and there's not many sources for it that I've seen.