Two new categories have been added to the 9/11 Timeline.
One of them is called 1993 Somalia Fighting and focuses on the lead-up to the infamous Black Hawk Down incident. Basically, it seems that associates of Osama bin Laden trained the Somalis in techniques to shoot down helicopters they had learned from the US and the British during the Soviet-Afghan War. This is probably why the Somalis suddenly got good at shooting down helicopters.
The second is called 2001 Attempted Shoe Bombing and looks at the failed December 2001 bombing of a transatlantic jet by Richard Reid and related operations. There are a number of interesting points here: the bombers were under surveillance for years, one of them was recruited by British intelligence informer Abu Hamza, and at least one of their contacts was arrested shortly after 9/11.
Expect to see some additions to these categories in the next week or two.