shademap.app - ShadeMap is a global simulation of mountain, building and tree shadows for any date and time. ShadeMap calculates shadow positions in realtime and displays them on a map.
It can display how many hours of sun or shadow a specific location gets over the course of a day and even over the course of an entire year.
[Firefox Relay] - Create an alias (fake address) for your email that you can safely use instead of your real email address.
Sherlock (Python Library) - Search for every trace of a person online (useful for finding and deleting every embarassing social and forum accounts of yourself from the web)