Psychedelicraft is an extremelly realistic mod about drugs.
It adds classical drugs (marijuana, cocaine, coffe, peyote, tobaco) as well as fantasy drugs (harmonium, magic mushrooms) and an extremely big variety of molotov cocktails, alcoholic drinks and drug teas.
The effects of all these are very realistic (in movility, mouse sensibility and player vision (shaders)).
It is sad that this mod was currently death (later update is for 1.7.10, and now it hasn't development for new versions).
Pages of the mod: