Combining GPS tracks with semantic annotations is the basis for large data analysis tasks that give insight into the movement behavior of populations. In this paper, we present a first prototype implementation of a GPS tracking application that aims at subsuming GPS tracking and manual annotation on a standard mobile phone. The main purpose of this prototype is to investigate its usability, which is achieved by a tiltand motion-sensing interface. We provide a GPS diary function that visualizes GPS trajectories on a map, allows annotating the trajectory, and navigating through the trajectory by moving and tilting the mobile phone. We present the design of our application and report on the very first user experiences.