Tube Map Live is a new app for iOS devices that tracks the locations of trains across the Underground network.
Upon loading the user is presented with the familiar Tube diagram, overlaid with a number of train icons that look like they've wandered in from Pacman. The icons, which are colour-coded to denote the line they're running on, slowly inch their way around the network. Tap on any icon to bring up further details, like the train's destination. There's also a useful bar at the bottom which lists the number of trains on each line (topping the list at the time of writing is the Northern line, unsurprisingly, with 91 trains in service).
Tube Map Live is a free download for iPhone and iPad, and is well worth a few megabytes of your device's disk space. Our only gripe is that the app only covers the Underground; the DLR and Overground lines aren't included.
The developer, Andy Drizen, also makes the Tube Tracker app, which bills itself as a comprehensive guide to using the Underground. It includes maps, directions to nearby stations, information on how lines are running and a journey planner. Though not essential for Londoners experienced with the Tube, it's still a valuable addition to your device. Tube Tracker costs £1.99.