How can I share a document library between sites or site collections

Dear NG,

How can I share a document library between multiple sharepoint 2007 sites and sub sites or workspaces?

I have serval document libraries that I want to share between multiple MOSS 2007 sites and sub sites.

I also want to be able to add and update the shared document libraries from any of the sites or sub sites
and have the changes show up in all sites that use the document library automaticaly.

Thank you for your answer.

Best