Matt Reed is blessed with working in a pet-friendly office. However, it has been known for him to completely lose track of his dog, Bean, and so he set about working out a method for tracking him. To do it, he attached a bluetooth beacon to his dog’s collar and then installed 3 Raspberry Pis to trianguate (or pi-angulate) the position of the beacon. It’s an ingenious system and he’s written an iOS app to visualise the floor plan and Bean’s position. Read more here.