Just completed a short piece, with Rob Kitchin, describing the importance of barcodes and RFIDs as identification technologies. It is for Globalization in Practice being edited by Nigel Thrift, Adam Tickell and Steve Woolgar.
This entry draws in large part on our 2005 paper, Codes of life: identification codes and the machine-readable world, Environment and Planning D: Society and Space, Vol. 23, No. 6, pages 851-881.