iPhoto Library Manager allows you to organize your photos among multiple iPhoto libraries, rather than having to store all of your photos in one giant library.
IPhoto Library Manager v3.7.3 MacOSX Incl Keymaker-CORE
iPhoto Library Manager 3.7 now available, with iPhoto 9.2 support
iPhoto Library Manager lets you easily create and keep track of multiple iPhoto libraries, but that's only the beginning. It also has the ability to copy your photos from one library to another, while keeping track of photo metadata that is normally lost when exporting from one library and importing into another.
Titles, dates, descriptions, keywords, ratings, faces, and place information are all transferred along with the photos, ensuring that you keep all that information you spent hours entering into iPhoto. iPhoto Library Manager also reconstructs events and albums with the same photos as they had in the library they came from, as well as retaining both the edited and original copies of each photo. You can split up a large library into multiple smaller libraries, merge entire libraries together into a big one, and much more!