As mentioned in the “how to” section of gifts, a great gift for one woman might be a disaster with a different one since for them, gifts are about knowing her and knowing what the gifts mean to her.  However, I will list here some gifts that have been meaningful to my wife:
Stuffed animals (there is a little girl in every woman, and gifts that remind her of this and allows her to embrace this is usually a good thing… ) crayons and a coloring book are good for this too.
A trophy for being a great wife and mom
A special thing that cools canned drinks super cold super fast
A towel warmer
A nice silk slip (generally lingerie from you is best when it isn’t too kinky, but instead communicates to her beauty and femininity.  I looked around (I warned the guys who are on the other end of my accountability website that week!) and really appreciated Wintersilk’s tasteful website, quality products, and good prices.
Her favorite movies and music – often before she knew they were out on video
Earrings that are connected to where I have traveled.
Special things from the kids – especially jewelry that she can wear everyday
Gift Cards for special places and then take her, or send her while I take the kids
A very soft Brookstone cuddle blanket
 
Footie pajamas
 
A soft drink or candy bar when I buy gas on the way home from work
When I travel more than a couple of nights, I leave little gifts for the kids to open every day.  Sometimes the toughest things about having the kids like that is there being no break.  The little gifts (often dollar store) give the kids something to do for an hour or two each day.
Whatever coffee cup she is drooling over at the coffee shop (she always wants one of them)
 
I will add more as I think of them, but I need ideas too!  Please add ideas here!