It's funny how counting time in weeks + months becomes completely normal. When you're pregnant + asked how far along you are, it's "ohhh, 34 weeks!". After your baby is born + asked how old he is, you reply "ohh, 13 weeks" or "27 months!". Interesting what motherhood does to you mathematical abilities.
Photo journaling is another take on recording the growth + development of your child in the early years. For my pregnancies, My husband takes a snapshots of the progression of my belly, each week marked with a post-it note with the appropriate week jotted down. Of course as a follow-up after our son was born, I took photos of him every week for the first year. I dressed him in a white onesie + stuck a post-it note with the corresponding week to him, having him sit in the same chair. In his 1st week picture he was less than thrilled being propped in a chair + was sadly screaming. For the 52nd week photo, Eliot is wearing a party hat + walking away from the chair he sat in every week.
The images of the sweet little girl above is another great example (images via flickr). Using the same orange chair + a pile of softies, Mom + Dad took a similar picture each week to reflect the development and personality of their daughter. Click on the link to see the whole collection.
When planning your photo journaling project, be sure to take into account the location + backgrounds that will be in the photos. Uniformity + unclutterd backgrounds is key. Having an object (stuffed animal or small toys) for your child to interact with displays their personailty + development.
Another dedicated idea is to take a picture of your child each day of their first year. This is exactly what new mom Raya at Paperpony blog has done, titling the series 365:a baby's first year. Photo journaling like this is more about the day to day details than the weekly growth. The overall effect will surely be a stunning collection of your baby + you'll be thankful to have all those detailed images.
Having a complete set of 52 weeks or 365 days is priceless.