Well maybe it doesn't make sense but here's some true stories I experienced.
(cliff notes at bottom)
2 stories :
1. Asbestos :
In 1987 while living and working in New York a co-worker says :
"You wanna make a shit load of money, then go work on the WTC.
I hear the WTC is in big shit trouble. They have been getting waivers to
remove asbestos and time is running out. The WTC has asbestos sprayed
on every single metal column of the building. The estimated cost to clean it
up is like a billion or even 2 billion. The place isn't even worth that much.
I know about the work because a friend has actually worked a little in some
areas. He laughs and jokes about these box like things on the interior columns
saying the whole place is wire to blow up. hahaha!
He's not the only one saying that either."
Fact : The WTC never completed the clean up project, there was still a billion
dollar job to do when it fail on 911.
2. Angry Eastern guy on street(1987) :
Me and a co-worker were walking during luch and talking about Isreal.
He was Jewish and just talking about simple life type things, nothing to make
anyone think twice.
Then this guy walking ahead of us turns around and started shouting and pointing
his finger in our faces and said : Rember this name, Osama Bin-Laden!
He shouted it 3 times.
Me and co-worker were like : Hey dude like WTF?? Who gives a shit?
The guy goes on to say that we will give a shit because Osama has a plan to
crash planes into the WTC.
We were like : Yeah right, BWAAHAHAHAHAHAHA!
That would just make us bomb the shit out him and won't change anything.
He then says there is also a plan to send anthrax thru the mail.
I told him I didn't give a shit because I had direct deposit. 
Cliff notes :
The stuff I was hearing way back in 1987 seems to fit too nicely into 911.
At the very least someone knew this shit was going down.
How can people say these things and pop it looks just like what they said.
The anthrax mailing appears to be home grown, but what a coincidence.
Was it a "copycat" who had known of the information the eastern guy was ranting about?
There was a lot of information out there; it was all a joke to me but I don't
work for the CIA. I might have thought different if I was trained in law enforcement.
So, this proves nothing but it's just too wierd for me to forget.