iPhoto Buddy is a Mac OS X application (Universal) that allows you to easily create, manage, and switch between multiple iPhoto Libraries.
Of course by putting a huge library into smaller ones, you get increased flexibility organization and speed in loading individual libraries. Even allows them on multiple disk drives.
Every time you switch libraries, iPhoto will relaunch because it can only have one library open at a time. Each library can be protected and even encrypted.
Any application that contains a Media Browser for accessing your iPhoto Library, can used with ANY of your iPhoto Libraries.
iPhoto Buddy requires a Mac running OS X 10.2.4 or later, and iPhoto 2 or later. iPhoto Buddy is fully compatible with iLife ’04 through iLife ’08.
It is donation ware.
See more information here.
