The Epson WorkForce DS-40 Color Portable Scanner ($179.99) is Epson's first portable with Wi-Fi and the first one designed to work with or without a computer. You can use it as personal desktop scanner as well.
Wi-Fi; Scans directly to mobile devices; Can use batteries or a USB connection for power
Simplex (one-sided) scans only; Manual feed; Unimpressive text-recognition accuracy; Doesn't handle business cards well