Vinegar as weed killer

 I read a few days ago that you could use vinegar as a weed killer. You fill up a spray bottle with undiluted white vinegar and spray the weeds and it kills them in 24 hours. So, I decided to try it on our own weeds. Here's what they looked like before.

Here's what they looked like after.

Not much of a difference. Although, it could be because we had a heavy rainstorm the next day, or maybe they're too big for it to work. I don't know. Does anyone know of a non-Round-up way to kill weeds? I'm interested in what has worked for you guys.