Well, Gertboard or not, has anyone done anything cool with the GPIO pins on RISC OS?
Let's see. Right now I'm running a home electricity monitoring station via Risc OS, with realtime graphing and data capture options using the TX/RX pins.
I've also been driving a vintage BBC Buggy around via the GPIOs. There were just enough I/O pins to accommodate all the lines on the Buggy's IDC cable. And the Pi was able to reliably read/write chips at the other end of that 5 metre cable without any signal boosting at all - which I thought was pretty impressive.
Similarly, I've been driving some tiny radio-controlled cars via a hacked controller connected to the GPIOs.
And I'm just now playing with one of those yellow and black Maplin/OWI robot arms on a Risc OS Pi (same as the arm used in the Scutter project in Mag Pi). Technically it's a USB program but I'm also using a redundant hand controller to drive the arm through the GPIOs and out to the USB interface. That way I can control the arm via screen clicks or via pendant switches, whichever is most appropriate at the time.
If anyone wants to see the USB robot arm and the home energy system in operation, I'll be showing them at the London Risc OS show in a few weeks time, along with one or two other Pi projects.
I'll be putting details of all this stuff on the Riscy Robots site when I get it properly set up.
At the moment it's just a holding page - and programming gadgets is more fun than building websites so it may be a while before it's all online.