Looking for a ""user defined collection" module

I am looking for a module that is designed to create what I am calling a "user defined collection". An example might be a "my favorites" collection, or a personal library collection. In both cases, the collection is a set of nodes related by User ID and an interface that allows the user to add a node to the collection, e.g., "add to my favorites".

Can anyone make any recommendations?

Thanks,

Ed