Ibutton, yup, 1-wire interface, power and data on a single line. Until now, ginagamit pa din sya and mataas pa rin ang market for that product.
Applicable sya sa harsh environment like kamote said. I don't know if they still test them here in Philippines. And nga pala dati syang product ng Dallas Semicon and naging maxim ng inaquire ng maxim ang DS.