With dimensions of : 3.66" x 2.56" x 0.35", it would be too large for a 12" doll but it's perfect for 16" - 19" dolls. They have miniature iPhones, too, but they are out of scale for these dolls.
Miniature Mac Laptop
Isn't this the cutest prop? It is a miniature Macintosh Laptop. No, it doesn't work silly! It cost all of $5.60, came all the way from China and took just under 3 weeks to get here.
Link to the seller: http://www.dealextreme.com/p/apple-macbook-shaped-cosmetic-mirror-silver-91010