RawMilkStar recently fixed up her living room and posted some cute photos of her family. I commented on how much I love decorating with photos and mentioned my photo wall. G.'s parents have two of these shelves that my FIL made when my MIL found directions in a Martha Stewart column in the newspaper. The wonderful thing is that they are shelves so the pictures sit flat and so you don't need to straighten them constantly, and you can easily rearrange/add/flip pictures without needing to move nails.
Here's my wall:
The three pics in the middle on the top row are my kids' 3 month pics; the three in the middle of the middle row are their 1 year old pics, and the three in the middle of the bottom row are their most-current pics. The others all rearrange and change.
Virtually everyone who comes into our house comments on the wall (mostly favorably...).