More information would help, what span of temperatures are you wanting, what sort of accuracy and resolution, and what sort of electronics capability do you have. There are many possibilities depending on your budget and application, these include NTC or PTC resistors, thermistors, diodes, temperature sensing Integrated Circuits, thermocouples, infrared etc. There are retail outlets like SparkFun electronics that have breakout PCBs with sensors on them, but it also depends on what and where you wish to make the measurements. A few more details and a more complete response will be possible,cheers,Richard
