WHO's tried them? What works and what doesn't?

I wouldn't recommend it, but if you must, then do not do it longterm and not more than once/week or preferably once/month (not the nootropics, they can be taken every day):

DISCLAIMER: If you kill yourself, it's completely your own fault. You have been warned.

hydergine, nootropin, ALCAR, pseudoephedrine, nicotine, and NMDAR-antagonists (the good stuff, NOT DMX) can work wonders. Can substitute THC for NMDAR-antag but will give you different experience. Can't say for other entheogens.

I have read on Erowid that Piracetam does enhance MDMA, LSD and Methamphetamine. It cuts ur tolerance to theese drugs and can make ur MDMA experience like your first time (wich is often the best and really magical/profound). It greatly enhances LSD effects making ur trip more intense and ur not feeling "fucked up" the next day. With Methamphetamine it makes you higher, cut the side-effect's ("disable" the crash) and cuts ur craving after the drug whore off...

I have a bag of Salvia I ordered a long time ago. Didn't notice much from chewing it and smoking is not for me . Never tried anything else.

I haven't noticed anything with Salvia either, smoking or otherwise. It's probably parsley.

Nootropics are also useful for ppl wanting to reduce the damage drug use does.