Mine is my guitar strap mod, using a couple of bootlaces. Acoustic guitars don't tend to hang too well for playing. They tend to hang so the face is away from you, which makes it harder to finger-pick; they're not held very securely bcos they don't conform to your body like an electric, so they can wobble a bit; and if you don't have a heel strap-button then tying the strap at the neck tends to result in it slipping off your left shoulder bcos the angle over your shoulder is very shallow.

But if you run a string from the base strap-button across the face of the guitar, and tie it off to the strap at your left shoulder, problem solved. The guitar is now held on both sides of your body so it can't move at all. Because the string runs across the top of the face of the guitar, the leverage pulls the guitar round so the face is more "upwards" and easier to play (it can also be used to provide better bracing for lap-style slide playing). And because the string pulls the guitar strap down at your left shoulder and holds it in place, it can no longer slip off.

Also useful if you're tying a strap to a guitar neck is to tie off behind the first set of tuners. If you tie off right behind the nut, the string tends to get in the way of your hand.

A thought for business trips. I get very bored in hotels, so I like to take my guitar with me. If your guitar case is a bit oversized for the guitar, it can act as a suitcase. It's long, wide and flat, so it's ideal for keeping shirts and trousers flat. And you can use the cutaway and waist areas for socks and underwear. If you're really desperate then you could destring the guitar and fill it with clothes as well, but I think that's going a bit too far! :-)

Graham.