It takes about 30 seconds to do this yourself in any image editing app, but if you're Photoshop challenged, iPod My Photo, will ipod sillhouette any photo for $20. You send them your photo, pick a background color, and they'll send you back the altered digital image within a week. Or better yet, read this tutorial by Jennifer Apple and start your own neighborhood "ipodifying" racket.
From Wired.