My home warranty company sent these guys out. I had a major leak under the upstairs shower and had a flight out of town in less than 12 hours. They came out quickly, identified the problem, went and bought the necessary part, and made the repair before I had to leave.
The only downside is that they had to cut a hole in my ceiling to access the leak and they didn't have the equipment and/or licensing to fix it, so we had to have a drywall company come out to fix things. (Oddly enough, it was another plumbing company that came out, but they had the ability to do drywall as well.)