For pilots and aviation enthusiasts I think that the ForeFlight iOS app is still the coolest thing ever. A while back they added the ability to inject external position, speed, heading and altitude data (as opposed to using the built in or an external gps). A neat application for this would be if you had your own drone. You could take the data from it and display it in ForeFlight. I don't have my own drone (yet) but I am experimenting a little with this and keeping a little github gist Perl script for it. I have not been able to get a Node.js script to work so far but Perl is a start for what I eventually want. If you find this kind of thing interesting you can find the gist at https://gist.github.com/dougtoppin/5237425