Gimp, the GNU Image Manipulation Program, is a great open-source cross-platform application for image editing.
Photoshop CS3 is “slightly” more expensive at $649, and is another popular image editing application
ThemBid.com has great tutorials on how to use either of these great applications to remove backgrounds from pictures quickly.
Here is the Gimp Tutorial: Removing Backgrounds Quickly in the Gimp
And the Photoshop Tutorial: Removing Backgrounds Quickly in Photoshop

[Via Lifehacker]
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