Imagine millions of connected sensors in an environment: factory, farm, government infrastructure, shopping centre, spacecraft, international currency market, biosphere, ... there are many applications and the potential benefits are great. But, what is the use without an intelligent way to gather, organise, and present or act upon such a vast quantity of data? This is a significant problem. Viewing the sensor network as a passive instrument, it is a data mining problem. A more adventurous approach is to regard the network of sensors and associated processors as a self-organising system that is aware of the data and able to form responses without human intervention. Many issues arise, for example, robustness, security, human interface, and longevity. I will report on two adventurous projects based on sensor networks: Ageless Aerospace Vehicles that has been running for about a year and is now developing a demonstrator, and Smart Spaces that is a new project funded as an emerging science area.