Having access to accurate position information is a key requirement for many wireless sensor network applications. We present SpiderBat, an ultrasound-based ranging platform for wireless sensor networks. It is designed to extend existing node platforms with ultrasound ranging capabilities. SpiderBat features four pairs of independently controllable ultrasound transmitters and receivers, which point towards different directions of the compass. Having multiple ultrasound transmitters and receivers provides an increased spatial coverage. Furthermore, our design allows to determine the angle of arrival of an ultrasound wave, which can be exploited for improved accuracy of the positioning.