I made this on a weekend back in April. My motivation was to create something I would find useful, and to utilize data provided by Toronto Open Data (http://toronto.ca/open).

The app uses the NextBus API to get live data on streetcar positions. A small PHP script converts the XML to JSON format, but the bulk of the app is Javascript. Thanks to the Google Maps API, the app works nicely on both desktop browsers and mobile.

I find that a map view works well for many different data sets, so I have started an effort to create a generic "on a map" boilerplate. This is a stripped down version of the TO Transit code, and includes the code to make it web app friendly on smartphones. It's still pretty rough, but here's a link: https://github.com/nomatteus/onamap