If you wade through the crap on Groupon and similar sites like LivingSocial, occasionally something good comes up. A friend and I recently went Clay Pigeon shooting, which I'll blog about sometime soon. A group of six of us recently went quad biking in Herefordshire via Groupon, which worked out at about £20 each. The company who run it do lots of other outdoor activities and are called Monnow Events.
We had a quick bit of safety training and the chance to drive around a test track. It's great fun and it feels like you're going really fast at times - until you look down at the speedometer and realise you're only doing around 12-18mph! We then went on a long trek through lots of fields with an instructor.
Overall it was great fun, but I think we would have preferred to have done some races around the muddy track for the whole session, rather than so much trekking through fields. We had forgotten that lunch was included, which was a nice surprise, however it turned out to be sausage sandwiches and I am a vegetarian! We found a nice pub down the road though so had a pleasant lunch there.
It was a fun experience and definitely worth the money with the Groupon deal. I'd like to try it again, but somewhere that organises some kind of tournament system would make it much more fun.