Simple may be a relative term for this project. It takes some soldering skill and electronics knowledge to make this thermometer. Everything about this build is well documented, and it really is a good place to start learning about I2C communications and electronics.

This thermometer can be used as a standalone thermometer with LCD display or it can be read out with a PC running Linux, Windows, MacOSX or solaris. BSD Unix and others are probably also possible to use for reading the temperatures. No special drivers are needed.

Make a Simple digital thermometer

HOW TO – Make a multifunction digital thermometer (in a mint tin)