Brailliant-32 can let users interact with mobile devices, but that's hardly portable. Guust Hilte's device is. Looking like a cross between an egg and a rubber stamp, or perhaps the abdomen of a Cyclocosmia spider, it features a series of what Hilte calls gullies on the top that users can trace over with their thumb to enter letters, shown after the break (complete with chill Röyksopp soundtrack). However, that's just a prototype, a Masters project at the Eindhoven University of Technology, with the ultimate goal to integrate the thing into the back of phones. Hilte's vision is users flipping over their celly, entering their message, and then sending away without looking. We think the same could be done without flipping, instead using your index finger, and finally making use of all that wasted space 'round back.