Okay I'll bite on this one, because there isn't much I haven't done.
Pot is by far my favorite, especially some of the strains of medical I've had. I always keep some around because its such a great sleep aid.
I coulnd't care less about anything that is methyl based (MDMA, Meth, Adderol, Ect...) or Coca based. I'm naturally ADHD and can do blow all night then turn around and sleep 20 minutes later. No point in it for me.
I've done Heroin a handful of times in highschool and that is a wild ride...A drug that makes vomiting pleasant is something to behold. I've also done tons of other opiates as well and there are some pharmies out there that will actually knock the socks off of Heroin...but I avoid those because being dope sick is not pleasant. I haven't touched anything opiate in over a year. For the record I've never shot anything.
Alcohol is always fun, but its also a cure all for depression. I stayed drunk for 6 months straight, going through about 2 gallons of gentlemans jack a week. When I cut myself off I went through two weeks of some of the worse sickness I've dealt with in my life. But alcohol usually turns me into an ass, so its probably a good thing.
Hallucinogens were fun...DId mushrooms and a few differnet types of blodder, but I grew out of it real quick.
I just came to the conclusion that I am problably older than most people in this thread :/