Use your Raspberry Pi as a Security Camera
Instructables have written a fantastic guide for using the Raspberry Pi and the Camera module as a home WiFi Security Camera.
All the hardware you will need is available in one of the following two bundles at the store:
Standard Visual Light Camera Bundle: http://www.buyraspberrypi.com.au/shop/raspberry-pi-camera-bundle/
Infra Red Camera Bundle: http://www.buyraspberrypi.com.au/shop/raspberry-pi-noir-camera-bundle/
For instructions of how to set up your Camera, follow the instructions here: