Source: a rationalist's interest in nootropics and stimulants, gwern's site, personal experience with the first four but no statistics. Typical modern person probabilities from discussions with acquaintances of various levels of openness. Summary of probabilities: nicotine and amphetamines are very useful but have negative associations that require high levels of rationality to overcome. Modafinil is very useful but seeing that and using it properly is probably a tad difficult for the average person.
Often, there are questions you want to know the answers to. You want other people's opinions, because knowing the answer isn't worth the time you'd have to spend to find it, or you're unsure whether your answer is right.
LW seems like a good place to ask these questions because the people here are pretty rational. So, in this thread: You post a top-level comment with some question. Other people reply to your comment with their answers. You upvote answers that you agree with and questions whose answers you'd like to know.
A few (mostly obvious) guidelines:
For questions:
For answers:
This thread is primarily for getting the hivemind's opinions on things, not for debating probabilities of propositions. Debating is also okay, though, especially since it will help question-posters to make up their minds.
Don't be too squeamish about breaking the question-answer format.
This is a followup to my comment in the open thread.