Memory books are a big part of the writing curriculum in our classroom. Each month, I take pictures of the children doing and learning many different things. I print them out and we spend several minutes reflecting on the fun things we've done or wonderful places we've gone to. I usually start off the year by writing short phrases or individual words on the board - this is so reluctant and/or beginner writers can have success immediately and more advanced writers have a springboard if they need one. Of course, our magic rubber bands get almost constant use.
We also use this time to practice specific writing skills - writing neatly and small, using upper and lower case letters and punctuation, having a space between each word, etc.
Not only are memory books a wonderful means for reflection, they also show writing growth as the year goes on. At the end of the year, the children proudly take their memory books home to share with their families.