baby leashes? input?

ok, I've always thought the leashes for kids were absolutely the dumbest thing ever and as I teen I was an asshole and complemented parents for their cute little puppies, but now that we're expecting our second baby, I've been thinking one might actually be helpful with our 3.5 year old. she likes to dart off and I can't exactly set an infant down to drag her back. I was just looking for humane input to this age old issue. maybe one of the bracelet thingys?