Gareth has a quick look at using the DS18B20 Programmable Resolution 1-Wire Digital Thermometer on the Raspberry Pi combined with the GPIO Tool Android App to monitor temperatures remotely.

https://play.google.com/store/apps/details?id=nz.org.winters.android.gpiotoolforraspberrypi&hl=en_GB

Datasheet: http://www.maximintegrated.com/en/products/analog/sensors-and-sensor-interface/DS18B20.html