If you want something fun and creative, here are some great ideas (and these would work not just for holidays, but also birthdays and anniversaries):
1) A book safe. My brother actually got me this for Christmas this year, and I absolutely LOVE it! What a fun and interesting gift! Plus, it will come in handy when I get around to making my "secret room" in the basement (which of course will have a hidden door behind a bookshelf, like all secret rooms should!).
2) A personalized Nook/Kindle/eReader cover. If your book lover happens to have an eReader, a cover can help to keep it safe (and make it more stylish).
3) A book purse. It is cute, and the book lover can use it to carry around a book he/she is reading currently!
4) Book Art. There is a TON out there to choose from, so if you can narrow it down by your book lover's preference it would help.
5) Objects made out of books. This covers many areas, including book lamps, book art, and even book jewelry.
6) Awesome book marks. I'm talking beyond the normal thin paper ones.
7) Book storage. For example, a book rack or a floating book shelf.
8) Unique Book Ends. These go well with #7.
9) Vinyl wall decals with a book theme. They would look great next to a bookcase full of books!
10) A book binding kit. Because one of the only things better than reading books is making your own books!
11) A book charger for his or her phone. It's more attractive than a plain charger anyway.
12) A book pillow. Perfect for laying back and reading a good book.
13) Fun book shirts. This way, your book lover can show off his or her passion for books.
14) Fun book mugs. Let's face it, I had to include this particular mug because it made me laugh (and sing a little).
You will notice that most of these options come from Etsy. That's because I prefer to buy handmade whenever possible, plus you can usually get the most unique gifts there! :) Most of these you probably wouldn't be able to get by this Christmas, but it never hurts to start planning for next holiday season or to pick up a gift for an upcoming birthday!