If you're a fan of yoghurt for personal taste or perhaps commercial reasons, this project by Instructables user "mschutze" will be of interest. After learning how to create a yoghurt maker than can produce around one US gallon at a time, they've created an Arduino-controlled device to generate and maintain the required temperature of 43 degrees C inside the chamber for perfect bacteria growth. Doing so is quite simple - using an Arduino to monitor the temperature with a DS18B20 digital temperature sensor, it can then control heat generation via a power resistor and a relay.
It's simple and with a little work the electronics could be reduced into a more compact enclosure. Nevertheless visit the project page for more information. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
To get started with your own temperature-controlled projects, consider using our TEMP: DS18B20-based temperature sensor module:
... or our HUMID: Humidity and Temperature sensor module based on the popular DHT22 sensor unit. Both modules are fully documented and easy to get started with. These are only two of over a dozen of our sensor and outputs modules.