I think the two best options are Picaboo and My Publisher. There are some exceptions, Blurb has some unique advantages that might interest some. If you have a Mac, iPhoto puts out decent books but they have Apple branding on them which is more than the others, more expensive, and of lesser quality.
My Publisher has a Costco discount if you have that, free download from Costco site to enable discount and have very easily obtained coupons from buy 1 get 1 free to 40% off through the usual coupon sites. (Costco applies a 20% off discount, so if getting 2 books the buy 1 get 1 is usually better)
I've used Picaboo for cards. Their card options were better than My Publisher, but if you want full bleed books (the entire page is a photo with no text) then My Publisher seemed to be cheaper and the software nicer. If you like more of a scrap book style, Picaboo would give you more options in that direction.
My Publisher's software is easiest to use other than iPhoto.