This past weekend's hack project was http://MapDistanceCalculator.com. Click to add points to the map and double click a point to delete. The distance (in miles, kilometers, feet, etc.) is shown at the bottom of the page.

I made this because I like to see how far I would be running when I plan to run some place new. It is critical to know how far things are so you don't run out of steam somewhere far away! Similar tools already exist but none that I'm aware of give you a full screen map with easy to edit points.

I plan to add a save/export feature but I'm open to requests. Let me know what you would like to see!