Digital Precursor – Digital Precursor is the successor of RogueSci.org, the explosives and weapons forum that was regarded as one of the best underground forums and was pretty much in a class of its own in terms of the seriousness of the content. Alexires, a mod from RS founded DP not long after it shut down and together with the users is building a library he hopes to release as a download. Having seen this library, I can tell you that it will probably be the greatest information pack on fringe related discussion ever to be released.
Head over to DigitalPrecursor.org and check it out!
There are a lot of other sites that I’m not affiliated with but have great posters on a variety of really interesting topics.
Check out Quora! – Quora is a Q&A site – It’s like a much more adult version of Yahoo Answers, where those answering and asking questions aren’t brain dead morons! There are a lot of very successful individuals answering questions so its well worth checking out.
Bluelight – A massive forum/resource on drugs and pharmaceuticals.
Erowid – Similarly, a massive website full of trip reports and resources of every drug known to man. If its been abused, you can bet money Erowid covers something about it.
Lycaeum – A massive resource on drugs and a great forum too.