Maxim's iButton Thermochron temperature dataloggers are little silver doo-dads the size of a large watch battery that can record up to 2048 time-stamped temperature values. The internal battery is usually good for a few years of use. Maxim supplies a Java-based application for talking to iButtons to start recording or to download results. This program, coupled with a USB-based iButton adapter, works fine when you're just dealing with a few iButtons. But I have more than a few iButtons, so I used R to write a script to launch multiple iButtons quickly.