9-11 Research, the first truly in-depth study and collection of evidence. This vast work by Jim Hoffman is on-going. Many researchers depend on this material to develop arguments in further exploration of the events of 9/11.
9/11Speakout.org. David Chandler and Jon Cole provide a very accessible collection of descriptive pieces and videos based on the scientific analysis of readily available evidence.
Arabesque groups Pentagon witnesses. Arabesque uses witness reports collected by Eric Bart and stored by 9-11 Research, and groups them by content; whether they saw a large plane, whether they saw it hit, etc.
Spreadsheet of Pentagon witnesses. I have taken the same witness reports and placed their content in columns of a spreadsheet to enable easy calculation of the numbers in each group. I have included arguments that have been used to cast doubt on some witnesses and responses to these arguments.
Journal of 9/11 Studies, a journal publishing evidence-based articles on aspects of 9/11.
9/11 – A Call to Action, a video urging that the time has come to press for a new investigation. (Mar. 2012)