 Black Socks, a maker of men's dress socks, is embedding its products with radiofrequency microchips, or RFID technology. When scanned, each so-called smart sock transmits a unique ID number. The technology helps customers keep track of how many times their socks have been washed, how black their socks are, and which socks should be paired together. The cost? $189 for a 10-pack, a scanner, and yes, an iPhone app.