The EXPANSE LIFE concept seems interesting if you haven't seen it already:
http://blog.expanse.tech/post/149791717483/expanse-newsletter-vo-1-no9-912016-real

As with all these geolocation apps, it's how to prevent geo-cheating.

Will look into the other suggestions in this thread, Geocoin et al, as they sound intriguing and may help me get out the house a bit more