Mapnificent is a Google Maps application that provides a brilliant new way of looking at your local geography. Rather than letting you specify a start point and end point and then giving you directions and travel time, as most map applications normally do, Mapnificent allows you to specify a starting location and then see all the places you can reach by public transportation within a certain amount of time. This lets you pick an apartment, restaurant, or bar based on the amount of travel time you can tolerate. Someone hire this Stefan Wehrmeyer fellow (and not just for the fun accent).
This sounds a lot like our Accessibility mapper for the Twin Cities, which is multi-modal and does more. I assume this works off of Google Transit Feeds, which seems a reasonable approach for scaling up. Of course the video focuses on jobs (great) and coffee shops, which is the irrational target destination of 20-something planner types.