I got an email today with an offer from Shutterfly for a free 20-page 8x8 photo book (regular $29.99)! The promotion code is PHOTOBOOKS. You have until March 10th to create your book. If you're new to Shutterfly, you also get 25 free 4x6 prints added to your account. Shipping is $7.99. Additional pages (after 20) are $1 each.
Click on th 8x8 Story Book. Then press the orange get started button on the right. (Don't select from the "shop by occasion" list. Those are designer pages and your book will cost $34.99.)
I also found that you can get a free 20-page 6x8 softcover photo book (regular $9.99) from Picaboo. The promotion code is 1PFMDB-WE. The offer lasts through March 31st. You can get a hardcover instead, but you'll be charged $10 for it. Only the softcover book is free. Shipping is $7.99. Additional pages (after 20) are $.99.