HandWave is a small, wireless, networked skin conductance sensor that can be worn or used in many different form factors. Skin conductance is the best known measure of arousal (whether emotional, cognitive, or physical) and this device makes it easy to gather this information from mobile users. Many existing affective computing systems make use of sensors that are inflexible and often physically attached to supporting computers. In contrast, HandWave allows an additional degree of flexibility by providing ad hoc wireless networking capabilities to a wide variety of Bluetooth devices as well as adaptive biosignal amplification. As a consequence, HandWave is useful in games, tutoring systems, experimental data collection, and augmented journaling, among other applications. The Handwave builds on the earlier Galvactivator project.