So you need a tiny gesture-input device for your projects? You may want to give touchIt a look. It measures 60mm x 22mm in size and comes with fine, coarse, and tap modes. You can pair the device with Raspberry Pi, Beaglebone, Arduino, and other comparable solutions. A 3.3V or 5V supply is also required.
touchIt could prove useful for DIY electronics projects. You can find out more about it on Kickstarter.