That sock thing would be a great gag gift. Too bad at work we are doing a boring ornament exchange this year.
Lets get more ideas. I got socks to fill for the mantel and still can't think of what to get the wifey...
What does she like in general? Cool clothes, cosmetics and perfumes are the most popular stuff for women. Also a new good tech gadget (my girlfriend for example was very glad to get a new smartphone for last Christmas), tickets for different events like concerts of fav bands and experience gifts are unreal things in this case too! Especially the last ones if you're completely stuck with other ideas, there's so many interesting of them, including great romantic ones for couples.
Also for me the easiest choice in case of gifts is the one connected with person's hobbies, usually they're the best among all other variants
I can recommend paper books, music CDs/vynils, comics, pencils for drawing and other art things for creative guys, wooden models
, figures, sport cards for collectors, sport equipment and tickets for sport events, tours for travelling abroad (but it's not a cheap thing usually)... Animals can be a good idea too, however only if you know definetely which one is wanted and is the person ready for getting one. I mentioned this because sometimes such gift can create only problems because of some reasons, not pleasure.
And maybe she likes handmade art? If yes, I'm sure that she'll be glad to get smth which belongs to this type