Dude! How cool would that be? You could take it a step further, make it a Google Maps type experience:
* Enter start point
* Enter destination
* The software plots out the best route, including points of interest along the way
* It also generates appropriate random monster encounters, complete with stat blocks and where the monsters are met--the DM can hit "reroll" if he doesn't like the particular monsters generated (the DM can also set a range of ELs)
* The software can print out: the zoomed-in start point, zoomed out overland path, zoomed in destination, and randomly-generated (but appropriate for the terrain) battlemaps for any encounters
That would be
so rad.
Even something super basic (but setting-specific!) would be fun. Like, real-time weather for the Realms. Just query the WotC site for a particular town or region, and it tells you the current weather for that area (including a cheat-sheet for any rules impacts). That way, every group playing in the same area of the Realms can have the same weather.

Admittedly, there are much more important/useful feature but campaign-setting weather would be a fun little toy.
Make it super-accessible, so you could easily grab this info via, say, a phone's limited browser.
-z