@roloway, welcome to MobileRead.
The closest existing plugin to this is the "Reading List" plugin which you can find in this forum. With that plugin you can build your own lists of items to send to your device or store a preferred reading order.
However it has no external integration for sharing with other users - you cannot give your list to someone else or import someone elses. There are a whole bunch of issues you would have to figure out answers to. Things like how does a book on someone else's list get "matched" against a book in your calibre library (there would have to be some kind of manual comparison or "fuzzy" search). There is no single "id" that you can use to automatically match books between different libraries and book editions.
Also if you are sharing publicly you would have to have some hosting involved for the "hub", and preferably some kind of search facility so you could find lists of interest etc. Perhaps something along the lines of Amazon listopia or something.
It is a very nice idea though - I would love to be able to download a list of people's favourite scifi/fantasy/classic titles and compare that against my library to see what else I should be buying.