I'm new to Geocaching and I was wondering what else I've been missing out on. I didn't know where to ask this but if you know and love any similar adventure / exploring services please share!
A derivate of Geocashing is Geohashing, which started with an xkcd comic. The basic principle is the same: you take a pair of coordinates and try to get there. What differs is the way these coordinates are generated. As the page linked above describes, they are generated randomly each day for each 1°×1° latitude/longitude zone. A good place to look today's location for your area is geohashing.info.
You won't find any treasures at the end (usually...), but it's a fun way to explore the countryside around you. You might go somewhere and discover places you'd never go to otherwise.