I've recently started using Citymapper for iOS and have found it to be quite simply the most useful app on my phone. 'Next level' usefulness, stemming from great UI that shows you the time and cost (in money or calories!) of making the journey by foot, bus, underground/train or taxi. It turns out in London 'by foot' is a much more viable option than you think once the overheads of other methods are taken into account.

Weird thing is - it doesn't seem to use real time data, just uses average wait times, based on timetables. Turns out in London and Berlin where I use it, there are so many transport options that average wait times, (when known) never seem problematic.

That said, combine in real time data then clearly choosing routes becomes easier.

After that combining in data on how loaded each vehicle is makes things a whole lot more efficient. Ie 'walk 2 mins extra to this other stop as this next bus is rammed'.

Good times!