Once you create your digital layouts you can easily store them online, share them in galleries, or create slide shows with them; however, it often nice to print them as well.  If you have a nice printer at home you can size your layouts appropriately and print them on photo paper (there are even 12x12 inch printers you can buy).  There are also many places you can upload your images too and print them online.

Costco: If you have one near you this is a nice option, especially if you want to pick them up in person and not pay for shipping.  They offer a variety of sizes and you can also combine some layouts on one canvas and print them together for a discount.

Persnickity Prints: Just for starters this site offers great prints of layouts and the ability to print photo books of your layouts.  However, they are working hard to cater to digital scrapbookers by also offering all sorts of tips and freebies on their blog.

MyPicTales: This is another site dedicated to helping people print their scrapbooking layouts.  Their pricing for single pages is one of the cheapest out there.  They also offer photobooks, calendars, and more as options for printing.

Artscow: At Artscow you can print your images on just about anything from mouse pads, to stationary, to more traditional pages or photo books.  This site offers many discount coupon codes throughout the year, but know that shipping can take a bit longer with them sometimes.

Shutterfly: Shutterfly was one of the original online places for creating photobooks and other photo gifts.  They offer a lot of templates where you can simply upload pictures to, but they also have options where you can upload your whole scrapbooking page to be printed.