This year marks the tenth anniversary of 9/11, officially known as the 9/11 Day of Service and Remembrance.
You can also browse a number of websites commemorating the event. Here's a partial listing.
Here's more information on participating in the 9/11 Day of Service and Remembrance. What will you do in tribute? Please share your thoughts in the comments.
(Thanks to Karen Laughlin for her help on this post.)