How can I let users create multiple custom lists of favorites or bookmarks?

I want to give users some sort of "add this to bookmarks" link on all nodes of a certain content type. I'd like them to be able to create and manage multiple lists of bookmarks, and be able to share or send a list of bookmarks to other users (either by email or on-site messaging, doesn't matter).

It seems like Flag might be able to do this, but I'm unclear on whether it would handle creation of multiple lists of bookmarks per user.

Any ideas on how this could be done?

Thanks.