Some time ago I bought an Android tablet and was looking for good navigation software for walking (I do not own a car;). Being used to AGTL on Nokia N900 I first tried android counterpart, aagtl, but wasn’t impressed. Afterwards I discovered ViewRanger.
Downside of this software is that it’s not Free / Open Source. On the other hand its features are really impressive. Among them is ability to download OpenStreetMap tiles for offline use. It s also possible to buy commercial maps inside of the program. These are the same hiking maps you can buy in a book shop – Ordnance Survey in the UK and IGS in France. Bonus is that you can more accurately choose which areas to buy, even while being on the trip and deciding plans for the next day.
Overall it worked quite well during trip to Alpilles this summer – navigating with a large screen tablet equipped with GPS is really convenient. Only problem was that it sometimes went crazy due to 40°C heat, so occasionally I needed to fallback to a paper map.