Photos of seven of the hijackers before they were hijackers (i.e. before they allegedly went to Afghanistan for the first time) are available.
The first three were easy:
Mohamed Atta (alleged pilot, American 11):
He is shown with his father.
At the beach.
http://www.spiegel.de/img/0,1020,515643,00.jpgWith his parents.
Here's his Florida driver's licence photo:
http://www.theage.com.au/ffximage/2004/06/18/19ATTA_R,0.jpgAnd here is the day before 9/11:
He's on the left, the guy on the right is Abdulaziz Alomari.
Ziad Jarrah (alleged pilot, United 93):
Getting down on the dancefloor:
Flying to Germany with a relative:
Here's the standard FBI one:
Hani Hanjour (alleged pilot, American 77):
Here he is at the start of the 1990s
And here he is a couple of days before 9/11 with fellow alleged hijacker Majed Moqed:
Hani is on the left.
The other four were harder.
Marwan Al Shehhi (alleged pilot, United 175):
He's on the right. This was taken at Said Bahaji's wedding, which was held at the Al Quds mosque in Hamburg in October 1999. Another still from the same home video can be found in Perfect Soldiers by Terry McDermott.
Ahmed Al Nami (alleged muscle hijacker, United 93):
The photo was published in the Boston Globe, one of whose journalists travelled to Saudi Arabia in February or March 2002 and spoke with the family.
Here's his FBI photo:
Waleed and Wail Al Shehri (alleged muscle hijackers, American 11):
I guess the boy on the right is Wail and the baby on his dad's knee is Waleed.
The photo was found at the 911myths page on the 19 marytrs video. I presume it was obtained by a US broadcast journalist who interviewed a family member in 2002.
Here's Wail at an ATM in the US:
And here's Waleed:
As far as I know, there are no photos available for the other hijackers pre-dating their involvement in the plot.