This is the unofficial Wiener Linien app to display departures in real-time, calculate routes from A to B, find stops and check time schedules.
Nether Quando is also the official schwarzkappler.info Windows Phone app.

This app offers automatic departure time refreshes, graphical display of routes on a map, locating your GPS position and finding the stops near you, listing service interruptions, online shop for tickets, warnings about ticket inspections and very customized settings.

It's possible to quickly access past stops and routes with the built-in history. It's also possible to add often used stops to your favorites or even pin them to your start screen.

Nether Quando is completely free of charge and has no ads of any kind.

Uses Open Data. Data source: Vienna – data.wien.gv.at