Add the Canon Selphy CP400 ($149 direct) to the growing list of dedicated photo printers for 4- by 6-inch photos. Similar in many ways to other printers in this category, it's easy to set up and use; it can print directly from PictBridge cameras or from computers (but not memory cards); and its output is smudge- and waterproof thanks to thermal-dye technology (also known by the misnomer "dye sublimation"). It also brings a few extra tricks to the table, including the ability to print on a variety of paper sizes, from credit card size to 4 by 8 inches (though most people print at 4-by-6).