Memories are priceless, so it's no surprise that preserving them has become a major part of our lives. Americans take 55 million photos each day (that's 20 billion a year!), and more than a fifth of households save those pictures in memory albums. It's become a booming business as well: The "scrap booking" phenomenon has ballooned to a $1.4 billion industry. We buy millions of scanners, digital cameras, camcorders and other high-tech tools annually.

While we're continually embracing new methods and technologies to capture family memories, our motivation hasn't really changed. It's partly the fun of looking back and recalling specific moments in time. But there's another, deeper desire behind our photos, scrapbooks, videos and other keepsakes: to immortalize some part of ourselves and our families, so future generations can know us in a way we wish we knew our ancestors.