Ever knocked your guitar out of tune in the middle of a set (or, more likely, casual get-together)? Maybe after your all-acoustic version of Nirvana’s greatest hits, or, more annoyingly, after lending your guitar to someone a bit slap happy? Well, that’s what Tropical Tune ($300) was invented for.
Basically, you slap it on the back of the headstock, turn your guitar, and you’re good to go. If you start slipping out of tune, the device automatically puts you back in tune. Its battery is good for 300 tunings, or approximately one Grateful Dead jam session.