I third Romulan Ale.
It’s blue and Romulan… two of my favorite things. What more do you need?
Melange. It increases your awareness, quickens your reflexes, turns your eyes blue and gives you a lifespan of 300+ years. Makes it worth the complete dependance and deadly withdrawl symptoms.
And there’s a slight chance it can turn you into a demi god.
Pssst. Adhemar…
Read this. Please.
Hmmmm, does Suck Salt from Trek count? If Romulan Ale does I guess this does too 
They are a “nasty habit”
Cowboy Bebop: RED-EYE - Spray this stuff in your eyes, they turn red and the world seems to move slow, making it easy to dodge bullets and kick butt.
Serial Experiment Lain: Accela - Not a drug, but a pill (A SCARY looking pill, it spiky and you swallow it! I still wonder why you need to take it out of the gel cap before swallowing.) that acts like a drug. It causes the brain to create a hormone that speeds up one’s perceptions, making the world around seem to slow down.
The video experiences in the movie Strange Days weren’t legal, I think, and they could be really neat. And really bad. I always found the idea intriguing.