As it turns out, there is a 9/11 Memorial Museum that does accept donations of general TwinTowers memorabilia, which includes photographs, as well as other types of memorabilia. The museum is also getting ready to open a memorial of all the victims and is accepting any personal memorabilia of the victims, such as journals, letters, video footage, audio footage and even personal effects from the victims.
A quick phone call verified that the photos can be hard copies snail-mailed or digital copies emailed to them. They may or may not decide to use the items, but it gives the items one more chance to stay out of the landfill.
They did say that they would like to have the contact information of the donor sent along with the items so they may send a letter back. I was also told that they do receive quite a number of donation inquiries, so it may take a bit of time to send a reply.
The 9/11 Memorial Museum website is www.911memorial.org. Digital files can be emailed for review to firstname.lastname@example.org. Any additional questions can be answered by sending an email or by calling 212-312-8800 or 877-671-1636.