Multiple sites to one specific database table.

I have multiple WordPress sites that each have their own content for the most part. In some cases, however, rather than duplicating content from one database to another, I’d like to have one database with the “common to all sites” tables and read that.

For instance, I use the NextGen Gallery. I would like all the galleries available to all the sites so instead of copying all the ngg tables to each database is there a way I could have a separate wordpress database with just the ngg tables, have all the sites get those tables from that database and still get all of their local data from their own table?

Would love a link that would explain this process if one is available.