ToT: ThisOrThat - Let your friends choose this or that for you
Zenly - Zenly is a GPS tracker to locate your friends in realtime.
sup - The first creep-free way to see nearby friends
YouMap - The Human Atlas™
Mu4e - Starting with version 0.9.8, mu provides an emacs-based e-mail client which uses mu as its back-end: mu4e.
Avoid Tourist - A crowdsourced map of touristy places to avoid 🗺️