I'm an experienced drupal developer (tons of sites in versions 5-7 over the years, all custom themes, some custom modules etc), but I'm coming across a use case where I'm not sure how to approach it, looking for suggestions on where to start, whether there are modules that will help with this (multi-site will not for example solve this issue).
What I want to have is one central install of drupal maintaining a core data set. Other installs of drupal (eg. on laptops) can download sections of data from that main application, then go offline and run with that data locally, which may get updated during that time. Later, when the remote instance(s) return online they will automatically sync any changed data to the primary application.