DigitalUnicorn
Bluelighter
N,N-DMT & Mescaline are the only two that fit the obsession criterion for me that I've not yet tried. Ganesha would be the same except my doubts about availability have curbed desire.
Drug I am currently obsessed with: Heroin. I almost bought some today, but a really good deal on OC 15s came up instead. I suspect that trying heroin would be the beginning of the end for me, but that doesn't stop my desire.
Crystalmeth.
Almost impossible to find in the UK
*I JUST realized i've never had any barbiturates, can anyone comment on how the effects are of, say, some phenobarbital?