I'm a bit of a keepsake 'nut' I have a black artbook book going with documents, cards from family, and any letters or bits and pieces with captions under each thing. I also have a 'baby record book' on the go and finally, my favourite is the massive digital photo book that I have going which im going to get printed on my bubba's first birthday and hopefully will keep up doing one per year. I'm only having one child so documenting everything and remembering it all is important to me.
i have everything in a box atm, lol. i kept the balloon that said "it's a boy" and all of the congratulation cards, immunisation letters, car capsule letters, even his umbilicol cord thing.. i kept everything but haven't put it into a scrapbook yet.
You can maintain a photo album. This is best way to record the memories of your children and their lives. Thanks.