I'm surprised no-one has offered iPhoto Buddy as a possible solution.
It allows you make as many Libraries as you want.
I've swiped a quote off the webpage
http://www.iphotobuddy.com/
which says it well:
"
iPhoto Buddy is a Mac OS X application (Universal) that allows you to easily create, manage, and switch between multiple iPhoto Libraries. The advantages of splitting your One Huge Photo Library into multiple, smaller ones include improved iPhoto performance, increased flexibility in organizing your digital photo collection, and a consistency with most other Mac applications that allow their respective data to be stored in as many documents (in this case, "Libraries") as you like.
i
Photo Buddy uses a simple, streamlined interface that was inspired by iPhoto itself. Anyone that has used iPhoto will immediately feel right at home using iPhoto Buddy. It truly is a companion application--a real buddy!
iPhoto Buddy will never alter/move/delete your Libraries or your photo files. It's perfectly safe!"
Great little programme and the owner asks for a donation. I reckon he deserves to do well. I have found it has made iPhoto much more functional as working with smaller Libraries is much more economical with resources.
For instance each country could have its own Library....As many Albums as you like within each Library.
Hope this is useful, or did I miss the Point?