Smart Bus allows you to monitor real-time arrival times of public transportation using data from OneBusAway (http://www.onebusaway.org).
In order to add new stops to your favorite list, you need two pieces of information: the ID of the bus stop and the IDs of the buses going through that stop.
To look up stop ID and route IDs, use the web tool on OneBusAway website and open Fiddler to inspect the request payloads.