Tree Catching is an emerging hobby that combines a nature walk with technology. Trails are set up by attaching QR code to designated trees so you can learn more about the trees as you hike. According to this piece in the Toronto Star it is catching on in many US and European cities and now ACER has set up some trails in the western GTA and Niagara region. I don’t know if there are trails elsewhere in Canada.
Tree Catching might make a nice alternative to geocashing if you are looking for ways to integrate technology into your program.