Apple Thoughts: Image Extraction Made Easy

"Decompose is an application allowing an easy and flawless extraction of elements from pictures in order to use them to make composite images. It is the perfect tool for making images for web pages, newspapers and magazines or simply for your own creations."

Decompose is from Metakine saves the extracted image as a TIFF, and also corrects colors to remove the previous background. You can try this out for free in demo mode, or can purchase the full version for $29.95 USD. They also have a set of video tutorials to help you make your decision, and this requires Mac OS X 10.4.