I know there's a long thread for iPhone/iPad apps. but those are general and those that relate to travel are things like TripIt which are for travel planning.

But what about those you would use while you're out and about? Most people know about international data roaming rates so they either try to get an unlocked device or turn off data roaming.

Well I'm going to try to use a Wifi device in Italy so now, I'm interested in apps. which make use of the GPS and compass.

Obvious categories are things like photo apps. which will geotag. The Lonely Planet apps. and other guide apps. seem to use Location services to show where you are relative to tourist attractions or recommended hotels and restaurants.

Also would be interested in a good augmented reality app. but going to Sicily, which may not be as well-covered as places like Paris and Rome.

Anyone been able to use iPhones/iPads for travel purposes beyond travel-planning or the occasional browsing at Wifi hotspots?