I want to try EVERYTHING. Nothing is really offlimits.
Unfortunately I've done just about everything. There are plenty of obscure RC's I've never done, of course, as well as a whole pile of less-than-popular opiates, but I've done everything I could find.
Left on the list:
PCP
Nitrous Oxide (surprisingly, I've never been offered it! and I'm too lazy to go through the whole ordering-canisters-and-a-cracker thing for a 1 minute high)
Crack (though I've done plenty of coke)
EDIT: I'd love to find oxymorphone (Opana), I've read such good things. It's the only opiate that REALLY sounds awesome that I've not yet tried. Done heroin, morphine, oxycodone, hydrocodone, fenatyl, codeine, and a couple others I can't recall atm.
I'm PLANNING on doing 5-IAI, "Benzo Fury" (god I hate that name), and MDAI. I'm considering AMT, but I've read reports of people tripping for 24+ hours, and I don't usually like drugs that last anywhere over 6-8.