HP's Sprocket 3x4 Instant Photo Printer, not much bigger than models for wallet-size output, churns out decent-quality 3.5-by-4.25-inch pics on the go and without an ink cartridge.
Canon's improved IVY 2 Mini prints good-looking photos and stickers at competitive running costs, making it an excellent smartphone companion for little on-the-go pics.
The inexpensive Kodak Step Instant Mobile Photo Printer churns out attractive, business-card-size photos with adhesive backing at reasonable running costs.