This module enables you to easily control upto 2 high-voltage loads over an SPI interface, lightbulbs for example, or your coffee maker (mmmmmm, coffee...).

The board is equipped with 2 SPDT relays, with all (2 x) three pins connected to screw connectors.

The PCB is equipped with two I2C connectors, so daisychaining multiple I2C modules is an option.
This allows you to control the relays with 2 data lines (SDA and SCL). This makes it possible to chain multiple modules without the need for more IO pins!
The board can be used with all microcontrollers, such as the Atmel AVR, Arduino/Freeduino boards, Microchip PIC, etcetera. Other computers/boards with an SPI interface (such as the Raspberry Pi) should also be able to control this module.

The module comes with all connectors pre-soldered:
One male 1x4 I2C connector, and 1 female I2C connector, (one for input, and one for daisy-chaining).
6 screw-connectors for power and outputs.

Datasheets:
Documentation for the complete PCB
Note: The photo is of the SPI version.