It looks like we were not forgotten with the Witcher III bundle like initially thought. I didn't see this posted anywhere else so I do apologize if this is old news but I just found out a few minutes ago while loading up all my drivers in my new build.
 
There is a beta GeForece Experience feature that if you help test out and you own a Titan X installed on the machine you test, they give you a Witcher III key.
 
http://www.geforce.com/titan-x-geforce-experience-beta/code-instructions
 
Instructions at the link above.
 
Enjoy.
 
(Again, sorry if this is old news. I did search and only got 2 hits back for "Witcher")

We have talked about it in a couple of other threads.  No one will ever fault you for insuring that others know about something free, though.

Dave3d
I wonder if you already have the game on gog if you can get a gift copy to give to someone else?

You get a key, so you should be able to gift it to someone.

Kinfet
You have to link it to a gog account during the process, doesn't have to be your Gog account I guess 

They give you the key before you're asked to link the gog account. I didn't test it but I'd imagine you could just take the key to gog and activate it manually instead of through GeForce Experience.

That i see in my GeForce experience the day of the anounced, just click on the trophy on the top right of experience . Copy the code , go on 
and the step are easy. And download the witcher 3. I do not realy like gog galaxy it's a beta but you do not really see if your dlc or patch is instaled.

I did it, got the code, hope someone else can use it.
 
@killer:
Go to gog.com, and add the free dlc to your cart, and checkout.
It is free, but you still have to do it, to get the dlc's.
Then, you can use galaxy, or just download the 4 dlc's manually and install, so you know you got them.
;)
 
P.S.
You can uninstall the Experience afterwards.
:P