Drug: marijuana
Nicknames: weed, pot, reefer, grass, cheeba, bone, leaf, nugs, fuzzies, midis, buds, hash, ganja
Form: grass, block or oil. Usually smoked but can be brewed or eaten.
Effects: relaxation, heightened senses and sociability; paranoia, hunger, impaired memory

Drug: MDMA
Nicknames: Ecstasy, Extasy, E, X, XTC, Adam
Form: tablet
Effects: stimulant and hallucinogen, causes body temperature to rise.

Drug: LSD
Nicknames: acid, trips
Form: squares of blotting paper, tablets, cubes, microdots
Effects: hallucinations, flashbacks, bad trips

Drug: GHB (gamma hydroxybutrate) and Rohypnol
Nicknames: GHB: liquid ecstasy; Rohypnol: roofies, roach
Form: colorless, odorless, tasteless liquid
Effects: sedative. Can lead to blackouts, coma. Known as date rape drugs.

Drug: Ketamine
Nicknames: special K, K, vitamin K
Form: veterinary anesthetic powder. Can be sniffed or smoked with tobacco or marijuana.
Effects: dream-like, hallucinatory state, loss of sense of time, identity.

Drug: Psilocybin
Nicknames: magic mushrooms, shrooms, mushies
Form: small mushroom caps, can be made into tea, dried, cooked.
Effects: relaxation and hallucinations; the wrong kind can be poisonous.

Drug: cocaine and crack
Nicknames: coke, Charlie, snow
Form: odorless, white flaky powder with bitter taste. Can be snorted or injected. Crack is the "rock" form.
Effects: euphoria, alertness; paranoia, depression, insomnia

Drug: heroin
Nicknames: smack, junk, H, jack, horse, dope
Form: white or light brown powder. Can be smoked, injected, eaten
Effect: relaxation, relief; nervousness, insomnia, loss of sex drive

Other terms:
Blunt: marijuana and tobacco cigar
Bong: Water pressure chamber used to heat and smoke marijuana
Hit: a single dose or puff of marijuana or other drug
Joint: chopped-up marijuana rolled into a cigarette
Nick: very small amount (short for nickel bag)
Pipe: bowl, screen pipe and mouthpiece used to smoke marijuana
Rock: waxy, off-white chunk of cocaine, boiled into a pure form
Toke: to smoke marijuana or inhale cocaine
Sources: The Whale's Tale, Cascade, freespeech.org, On-line Dictionary of Street Drug Slang, clubdrugs.org, interviews