Hi, I live in Australia but am soon traveling to Europe (mainly London and Germany). Are there apps I can get for my iPhone and / or iPad that contain offline maps that i can access without having to enable data roaming? If so, will the GPS of my iPhone 3G still function in those applications without data roaming? My iPad is wi-fi only, so I'm more interested in iPhone apps if the GPS will work, but an iPad app would be great to be able to browse maps offline. Note that I'm not driving at all, so not interesting in car navigation apps, more so on foot.