|I'm not sure if this counts as accredited...|
Despite our initial reservations (when we showed up and were the only people there without an infant), it turned out to be a lot of fun and we learned a lot. I now know over a hundred signs for various foods, family members, animals, and other things that seem like they'll be really useful for a young toddler.
There was a brief snafu when we tried to come up with name signs for "Daddy Andy" and "Daddy Brian", though. Combining the sign for "Dad" with the letter "A" worked fine. But when we tried to do the same with "Dad" and "B", when inadvertently ended up with the sign for "bastard". Now, I'm not gonna go into whether I think that's an appropriate sign for Brian or not, but suffice it to say that we had to come up with something else!
It was also really encouraging to see some of the kids in the class start picking up on signs after just a few weeks. Some of them were as old as 8 or 9 months, and they really seemed to get it quite quickly. One in particular had 4 signs down by the end of 4 weeks, and it seemed like the floodgates were flying open!
All in all, a good experience, and I really liked our teacher (Nancy Hanauer). Highly recommended to anyone in the Seattle area!