A shape sorter, to me, represents childhood. It's one of the earliest toys I remember playing with. I like them because they bring together cognitive development as well as motor development. It takes brain power to match the shape with its hole and it takes motor skills to actually put the shape through the hole.
Shape sorters help little ones work on gross and fine motor skills. Picking up the shape and moving it to the sorter requires gross motor skills to move the whole are. Then, once the shape is at its hole, your little one must then rotate and manipulate the shape to get it to fit just right through the hole. This takes fine motor skills.
I feel strongly that every little one should have access to a shape sorter! There are so many companies producing a variety or styles of shape sorters so you're bound to find soemthing in your budget! Check out these shape sorters on Amazon.com.