Wireless sensor systems provide effective solutions for data gathering in wide range of applications such as industrial, agricultural and environmental. Usually those applications do not require high speed communication and intensive data processing. However, the emerging applications of wireless sensors in surveillance, medical and human interaction with ubiquitous computing infrastructure pose demanding requirements on the communication, flexible architecture of the sensing node, data processing and re-activeness of the system. In case of wireless interaction an additional requirement is compliance with mainstream communication protocols for personal use, which is not always the optimal communication solutions for new novel applications. This book is focused on investigating key technological aspects of wireless systems for interactive and locating applications. This book presents localized interactive systems that allow users to access services specific to their current surroundings and also explores the implementation of various wireless systems for intuitive interaction and localization.