A lot of people thought that digital photography would make physical photographs obsolete. But it seems people still want photos to hold onto, to press into a scrapbook, or to stuff in a shoebox. In fact, the competition between photo printing services is so fierce that vendors, from pharmacy chain stores to exclusively online picture services, are vying for your business with enticing promotions. We look at six deal-friendly photo printing services to see what they have to offer for the money.