What should I buy my wife for Christmas when she just lost her 18 year old son in a car accident? Anything meaningful? I need real advice!! thanks

They have memory garden stones, you could make a memory garden for her, have a bench there for her to sit and reflect.

http://www.thecomfortcompany.net/gardenmemorials.aspx

A beautiful locket necklace...your wife can keep a picture of her son inside it...Peace...

I'm sorry for her loss. No present will take away the pain of that kind of loss. That said, the Sony Reader - pocket edition is nice. You can buy her a journal to capture her thoughts at this dark time in her life - or membership in some sort of club or activity she enjoys - yoga, spa, ceramics, auto mechanics, whatever she enjoys, provides escape where time flies when she does that activity.

A series of religious, and missionary books teaching us the loss and victories of The Crusaders who had made our most honorful history chapters full of tear,and blood of martyrs that enlightened our lives over the dark stones of theirs in the graveyards from Russia to Spain; from France to America....

When my Daughter was killed by a drunk driver I really didn't want anything.
I didn't want to celebrate holidays or birthdays. For a long time I didn't even want to get out of bed.
The one item that I do have that I cherish the most (and perhaps your wife might like too)
It's a memory quilt made from my Daughters clothes. My sister made it for me. I sleep with it every night.
I loved it so much I had one made for each of my children and my Daughters best friend.

First let me say how sorry I am to hear such tragic news, and I am glad you are there for your wife. How about a scrap/photo book of all their precious memories together. You could buy a locket and have it engraved and his photo put inside. I like the memory garden idea. I wish you both love at this great moment of sadness.

The police photo's might allow a release of what if questions?

I am so sorry for your loss.. Perhaps a necklace with a pendant of something that he loved or that they shared. Something that will remind her of him everytime she sees it.