Route reversal. Ok, I know that'll get Tony's back up what with one-way streets, sliproads etc, but there will still be a lot of occassions where this could be useful.

I'm OK with that. For routes where I don't know if a plain reversal will work or not, I can still tell MapsOnUs to calculate the return route (it's one click on their screen). For significant portions of any given journey, a plain reversal would probably be correct.

The only difficulty from the coding side would be: For the text directions it would have to parse out things like NORTH SOUTH EAST and WEST and change those to the opposite heading on the reverse direction. However, how's it going to know what to change and what not to change?

Examples:

a) Merge onto INTERSTATE 80 SOUTH.
b) Turn RIGHT onto SOUTH MAIN STREET.

It would need to change it in example (a) but not (b).