You're faced with a folder full of images, and you need to sort through them, trashing some number and keeping the rest. For a quick way to do that, select them all, and open them in Preview (in Leopard, at least). You'll get a single window with each graphic as an item in the drawer. Use the arrow keys to move from image to image, and when you see one you want to trash, press Command-Delete to move it from its source folder to the Finder's Trash. (Delete by itself just removes the picture from Preview's drawer.)

From Adam C. Engst