Teetering across greasy shards of Snowdonian slate, we were glad to have spent time pretrip improving our balance on this German company's new-age tightrope. Popularized by Yosemite climbers, slacklines are the best tool we've seen for building stability for steep or sketchy trails. They're also the most fun you and the kids can have in the backyard without marshmallow guns.
Use the simple cam-and-loop system to string the webbing knee-high between two trees. Put one bare foot up and weight it until your leg stops quivering (the shakes are natural), then stand up and try to walk across. Price, construction, and setup are all top-notch, and Gibbon's two-inch-wide webbing beats the usual one-inch line, which requires a Yosemite climber's equilibrium to master. $79/$99 (15 meter or 25 meter); gibbonslacklines.com