Wysiwyg - We have a map of Oz on the wall and the deal with my parents (they are on a two year caravan trip around Aust) is that instead of buying the kids trinkets and the like, they send a postcard of every place they stop and we put a sticker on the map. It's working really well and so far we've tracked them from Melbourne to Coober Pedy. Find my iPhone app is a fun way to see exactly where they are too.
I think I will steal that idea and ask mum and dad to do the same. They are doing similar starting end of Nov they pick up camper trailer 26th Nov but in six month stints (as they live in UK so have visa and insurance issues with doing longer) - we want to do a big trip ourselves and will prob get their camper trailer once they have finished or if they decide to have a break for a bit ( I can see them doing US at some point).