Tens of thousands (or more) of people have started using a Raspberry Pi for various reasons, however over time realise that it doesn't have the GPIO potential of other development platforms unless you spend a lot of money on expansion boards. One easy way to bypass this is to control an Arduino or compatible board - giving the user access to a wide variety of hardware such as motor drivers, 5V logic control and a general buffer between the expensive Pi and experimenting. This has been explained by Oscar Liang who explains how to control an Arduino with a Raspberry Pi via the I2C bus. It's quite easy and code for both boards is provided.
For more information, visit Oscar's website. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're new to Arduino, the first step is a solid board for your projects - our Freetronics Eleven - the Arduino-Uno compatible with low-profile USB socket, onboard prototyping space and easy to view LEDs: