i'm surprised to see "pure MDMA" so many times in this thread, i mean, it's out there, you just have to look...as for me:
pure MDA (yes, legitimately clean, pure MDA, on quite a few occasions back in Huntsville, AL)
pure MDE (only twice, but most definitely delightful, and once again, yes, legitimately clean and pure)
2c-i (have only been able to find it ONCE, and went over 36 hours in one of the most intense, enlightening, and profound experiences I've ever had, along with it being one of the most visual hallucinogens i've encountered. the visuals were so detailed and complex and beautiful, i kept describing them as "electricity"...about the 36+ hours: i know, i know, NOT SAFE...i pushed the dosage to the limit with it though, and it was well worth it)
Oxyfast(liquid oxycodone, only seen it once)
Fentanyl (both patches and lolli's on a few occasions)
i know there's a few more, but i'm on the verge of nodding off into bliss at the moment and typing is becoming much less interesting...