* Timetabling or scheduling apps like Doodle.com - subjects pertaining to Graph Theory * Travel comparison sites that can find you the fastest flight route fr

* Timetabling or scheduling apps like Doodle.com - subjects pertaining to Graph Theory * Travel comparison sites that can find you the fastest flight route from A to B (and/or cheapest or some other type of constraints) - Graph Theory * LinkedIn network analysis apps such as Socilab.com - Graph Theory Basically Graph Theory is extremely important, with applications in domains such as: networking, linguistics, (bio)chemistry, pathfinding & GIS, social network analysis, matching (dating apps, organ donation, medical residency matching) etc. Edit: Another application is PCB design. The circuit to be printed is the graph itself, it should not allow edge crossings that would result in a short circuit.