What circuitry or electronics could be usefully built into outdoor equipment?

Mike Parsons would like to know what circuitry or electronics you think might be usefully built into outdoor equipment (be it pack, boots, clothing etc or even a new product entirely) and what e device/s it might feed into and linking to which sites eg Social Hiking. Focus on what you NEED or dream you need, dont bother about what's possible! What would make things simpler, easier, faster, more weatherproof or lighter?