This is the gear I've been using to record sounds at playgrounds recently.
These are Daphon brand piezo pick-ups. I bought them from Swamp Audio.
A first generation Zoom H4 and a Fishman transducer, which works like a microphone pre-amplifier and equaliser to increase gain and shape the sound.
Usually I beef up the bass since I'm recording with another pick-up also but I've long thought that piezo sound a bit weak -- which is what led me to experiment with guitar pick-ups on the large-scale aeolian harp built by Alan Lamb and Scott Baker.
A pair of closed headphones are essential, of course.
The small pouch from my friend Janine Middlemost holds spare batteries and SD cards, while the bag holds everything together while I'm riding around town.
Just noticed that both the pouch and the bag feature mushrooms, which is an interesting coincidence and makes me wish I had a magic mushroom story to give it relevance.
For the videos I'm using a Nikon D5100, usually with an old Nikkor 35-70mm f2.8 lens and a tripod.
P.S. Just read this interesting post on contact mic recording and it's worth having a look if, like me, you wonder why piezo sometimes sound a bit weird.