The 72 PPI Web Resolution Myth: http://www.photoshopessentials.com/essentials/the-72-ppi-web-resolution-myth/
NOTE: "A digital image, on its own, has no inherent resolution at all. It’s just pixels. It has a certain number of pixels from left to right and a certain number from top to bottom. The width and height of an image, in pixels, is known as its pixel dimensions, and that's all a computer screen cares about."
NOTE: "As an example, a 640×480 pixel image would fill a 640×480 pixel area of your screen. An 800 pixel-wide banner on a website would appear 800 pixels wide on the screen. No more, no less. And no matter what you set the image’s resolution to in Photoshop, whether it’s 72 ppi, 300 ppi or 3000 ppi, it will have no effect at all on how large or small the image appears on the screen."
NOTE: "Image resolution affects only one thing – the size of the image when it’s printed. By setting the resolution in Photoshop, we tell the printer, not the screen, how many of the pixels in the image to squeeze into an inch of paper. The more pixels you’re squeezing into every inch of paper, the smaller the image will appear when printed. And generally speaking, the more pixels you’re printing per inch, the higher the print quality."
Understanding DPI, Resolution and Print vs. Web Images: http://www.vsellis.com/understanding-dpi-resolution-and-print-vs-web-images/
Image Resizing for Printing:
Cropping and Resizing An Image For Final Output: http://www.zuberphotographics.com/content/printing/resizing.htm
Resizing Pictures to Standard Print Sizes: http://www.zuberphotographics.com/content/printing/resizing.htm
How to Resize a Photo for Printing: http://www.ehow.com/how_4442570_resize-photo-printing.html
Resizing Images for Printing in Photoshop: http://www.scrapjazz.com/topics/Computer_Center/Printing/916.php
How-to Resize an Image For Printing - Adobe Photoshop Beginner Tutorial [Video] : http://www.youtube.com/watch?v=biH-FSeu3RM