All not very useful when you're underground ;-)

True, although it might be possible in the future to install screens
around the stations/platforms that will show other lines, either at the
same station, or perhaps even on the next stations with interchanges.
Perhaps touchscreen panels on the platform (like near the information
point) that let you select a station and view realtime train info and
service information/updates.

This could be great for finding out if you'll make the next change, and
at night when the trains aren't as frequent, you can instantly tell if
you're going to need to run or not!

In fact, the whole journey planner could be offered on and around
stations for tourists too - in multiple languages. Not as a replacement
to staff (I suspect this would potentially happen, sadly) but as a
valuable alternative of real benefit to all.

Jonathan