I've used 5-MeO-DMT once. It wasn't a good experience for me, it basically generated extreme depression for a short (2-10 minute) amount of time. The taste was interesting.

http://en.wikipedia.org/wiki/5-MeO-DMT

EDIT: Huh, looks like it's the same chemical found on the Colorado River toad that makes you trip out. I didn't lick a toad to consume the chemical, myself. I had it in a granulated-sugar style form, and consumed it using what was essentially a crack pipe.



EDIT2: It's probably worth mentioning that this was in my early-mid teens and I had little experience with drugs at the time.