Magento offers Configurable Products so that it lets buyer selects attributes for a given product, like Size for Shirt, or Color for a Phone.
Problem is, you must add each possible single combination as a simple product, and that Configurable Product works merely as a container. This is impractical for attributes with too many values, and unexpected values.
For example it does not allow text values. What if a buyer wants to print his name on a Shirt?
What if I wanted to add a selectable attribute of tens of values? It doesn’t have to be a added through the admin area, hardcoded solutions are OK.
Something like Cart Item Annotation is there?
Configurable products should not be used for products that doesn’t have a physical definition, for instance Drawing and Designs. Instead it’s better to use Custom Options instead for these cases, where you don’t care about inventory of products nor attribute based statistics. This could be done through the Custom Options tab at Manage Product screen. Surely this eliminates the need for configurable products for a variety of cases.