eBay bought Kijiji.com, which permits animal listings (has a special category for it even), and turned it into eBay classifieds. So while they weren't permitted on their auction site, they're now allowed on this other venue. I find it a step back in their policies, myself.
I think it's great that BRAT lists their rescues on Craigslist. You know that they'll still have a screening protocol for them, unlike most of the individual resellers, which was one of my main concerns. Lots of rescues use Craigslist too. It's probably one of the first places people go to when they're looking for a local pet online. I've found out about a lot of local rescues that way, too.
The only "negative" thing, if it might be called that, is that some people who really have no idea how rescue works get all worked up over the adoption fee and start slinging false accusations about how rescues are in it to make a profit (ha!) when they ask for $200+ rehoming fees, while an individual who asks that much for a backyard-bred mutt will have their ads flagged because it looks suspiciously like a "sale." The rescue bashing that happens on Craigslist is really upsetting sometimes…
Interesting point about Petfinder. I hadn't considered that before (that all their dogs are listed in Texas).