THis is a (potentially) sweet mash-up of the new real-time data feeds from TfL (Transport for London)
Obviously TfL didn't think there would be any demand for live data on tube times and their servers have spiked so badly they shut down the feed after a week... very droll. Blog post
Old industries really seem to not get the industry in quite a dramatic way sometimes.
Anyway - expect dozens of real-time mobile apps as soon as it's back.
The mash-up is from Matthew Somerville at the Guardian's Science Hackday on 19/20th June 2010 : http://traintimes.org.uk:81/map/tube/
Here is a video: [flickr video=4730203122 show_info=true secret=8e1d05392e w=500 h=315]