Last-minute gift idea: A magazine subscription to their favorite magazine. Make it special by printing out a photo (found here or elsewhere on-line) best representative of the magazine. Put it in a simple black frame and wrap it with a handwritten note enclosed explaining the subscription length, etc.
Another way to make any gift special (last-minute or not), is to use an old photo as the gift tag. My daughter did this for me this year. She took a photo of the two of us from when she was just a few months old, made a black and white copy of it and glued it onto card stock. She didn't say a word about it and I was so touched when I saw it under the tree this morning. — Never mind what is inside, the wonderful memories that photo evokes is present enough already!
Well, I'm off to deliver cookies. Hope you enjoy your Christmas Eve. Isn't the anticipation for the big day about as much fun as anything?!