It used to be a problem to get good route planning on your smartphone when you are outside the country, because the roaming fees could plunge any McKinsey employee into bankrupcy when using Google Maps, which is only able to cache small map sections and basically has no way of telling you what is cached and what isn't. Rejoice! The OSMAND project provides an open maps and route planning solution which allows you to download all kinds of maps for offline use. I personally like the Android App even better than Google Maps: It's clearly for power users, there is much more to configure and you have more control. There is always an obvious argument for choosing another option over the kraken, but the option to download maps for offline use has to be the main reason why this is awesome. The entire Open Street Map project (see also the German version) seems to be a cool project which is worth contributing to, even if it's just pointing out a house number here and there.