Self Edge takes in-person drop-offs only at this point.
I've used these guys and been pleased with the results, although they seem to be better at indigo denim than black denim: http://htccalifornia.com/
I haven't had any repairs done by Railcar Fine Goods, but I was really happy with their tapering service the one time I used it.
Semi-related: One of the pockets in my Samurais has developed a hole. Any ideas for a cool fabric to patch it with? I'll probably just have a local tailor do it, but I'd rather bring in a scrap of something interesting than just take whatever crappy fabric they use by default.