Interesting uses of old mobile phones https://www.kickstarter.com/projects/topherwhite/rainforest-connection-phones-turned-to-forest-guar (I'm sure you'll how this be made applicable in other contexts (say, urban environment) and with other modifications). One group hopes to end poaching, WikiLeaks-style http://www.pri.org/stories/2014-07-14/one-group-hopes-end-poaching-wikileaks-style