OK, who had the book on Ian2 linking to his own apps in less than 1 hour?
I'm still using a Win7.5 phone, so my recommended apps don't take advantage of WP8:
MapSnap GPS if you like walking/hiking and already own maps.
Toilet Finder if you're out and about with young children.
I'm not involved in any of these projects, they're just ones that I tend to use.