There are a lot of interesting projects related with GPS tracking and web apps. For example we have a sites where we can track any flying plane in real time. Also there are such online trackers for cruise ships... Maybe you can make a web system which will track bitcoin wallets holders and show them on google map? So that I can see where the holder of this wallet at the moment: https://www.blockchain.com/btc/address/3FiMKffg2kY2Pi2Kebn2HZqN7m6kEcNUMk