iPhoto can hold over a quarter of a million images in a single library; that's a lot of pictures. But storing all of your photos in one library may not be the best way to organize them. Instead, consider creating multiple libraries, each holding specific types of images. You could have a pet library, a family library, portraits, travel, and landscapes. Or you could organize your images by less traditional criteria, such as things that are orange, shrouded by fog, close-up (or far away), or sparkly.

Courtesy of Coyote Moon, Inc.
Setting up additional iPhoto libraries isn't difficult; this guide will walk you through the process.
Create and Populate Additional iPhoto Libraries

