Bamboo makes a range of durable gear for pets, and sent in its Quick Control Collar with Built-in Leash, its Quick Control Leash + Seat belt latch, and the Quick Control Harness + Built-in leash. This was a year ago.
Why the wait? Well, they all work perfectly, but that's to be expected. Durability is the important criterion, especially when these simple items are made complex enough to qualify as gadgets. And that they do: the control collars have a soft handle that extends out from inside the hollow collar, acting as a kind of emergency dog brake, and the seat belt latch connects a leash to a seat belt, to restrict a dog's movement in a vehicle. They work, and work well–the latches kept our dogs safe but fairly free on a 1,500-mile trip, and the elastic collar-handles work well as a way to stop a pup savaging the postman, though they don't extend far enough to work as leashes, unless you're very short.
A year in, they're a little frayed at the edges, but the elastic on the quick control collar is still strong and the collars themselves have yet to show significant wear. One thing has failed: the little transparent plastic tag-holders. These went quickly, as they're no more durable than the plastic sheaths one might find on a file folder or the inside of a restaurant menu.
Product Page [Bamboo]