Sort of:
A girl in one of my classes asked me for help finding her a small breed puppy, she wanted to rescue, and I emailed her a couple of links to puppies on petfinder, and she did end up adopting one of them.
Also, my old boss wanted me to find her a rescue whippet - the dog I found on petfinder, however, was not a great fit, but the foster owner who had made the post was also a breeder who was rehoming a retired adult, and though she was a good fit for my boss, who took her.
Neither of my fosters were adopted via petfinder, either. One was through craigslist, the other had someone recommend us to her.