Podunk said:
Me I would go straight for the Mentats, from the Fallout series. +5 Intelligence and +5 Perception means I'd be able to work smarter and get more done, and I probably wouldn't even need glasses anymore! The whole addiction thing would be a small price to pay for pills that turn you into a genius.
Good news! I hear amphetamine does all of that except fix your eyesight! Apparently worked well for one of the greatest modern minds of mathematics, Paul Erdös.
*obnoxiously large image removed*
http://www.smbc-comics.com/index.php?db=comics&id=2245#comic
Not that I condone that sort of thing.
Me, since we're talking hypotheticals about fictional drugs, might as well go hog wild. Let me try some Psycho before an MMA fight, that'd be interesting.