JoCalc is tool for easy and intuitive calculation and planning of your trips (or any task where graphs are useful). Just add your cities, connect them by lines and attach the planned costs (tickets, hotels, food, etc.).
The result can be saved as a picture in PNG or SVG format (for example, to demonstrate it to your fellow travelers), or in an JoCalc format to edit your plan later.
Warning: JoCalc stores your data in the internal cache of the program. But this store is cleared with the browser cache. Therefore it is recommended to export your important graphs through the menu for saving to disk.