I've never owned a cellphone and I was looking through the store for stuff that I might find useful if I actually DID own a WP8 device. Along with MIDI controllers and virtual instruments, outdoor navigation apps would be quite useful for me.
I found this app while looking at GPS and geocaching apps. It's such a great concept because sometimes the paper charts are better than anything you can find online and I'm rarely looking for street maps anyway.

It's called MapSnap GPS for Windows Phone 7 by Simon McKenzie