We are proud to present a shield that we make, mainly for receiving FSK (and OOK) signals from sensors but not only. The shield comes with a duck antenna and demo examples.
FSK signals at 433MHz are very commonly used by consumer electronics devices including weather stations, power consumption meters, security systems, and home automation controllers.
The RF transceiver used is RF12 from Hope Electronics, this means that the shield is using SPI.
The advantages of SPI are that it runs at a higher data rate, and it has separate input and output connections, so it can send and receive at the same time. It uses one additional line per device to select the active device, so more connections are required if you have many devices to connect. Most Arduino projects use SPI devices for high data rate applications such as Ethernet and memory cards, with just a single device attached.
Arduino releases (from release 0019) include a library that allows communication with SPI devices.