The one we use, Alabaster Cleaners, has an online order form that's super convenient. They will pick up and deliver in one day provided you give them 4 hours' notice. They are pleasant, reliable, and follow our instructions to a T. Cost is $1/lb, with a 15 lb minimum.
We recently read about Blue Water Laundry in Daily Candy. We live outside their bailiwick (the financial district, Marina, Cow Hollow, Union Street, Upper and Lower Pacific Heights, Nob Hill, and the Presidio), but we like that they use environmentally-friendly cleaning products and practices. At about $26 - $31 per bag, they may be a smidge more expensive. (It's hard to compare without seeing how much fits in a bag).
As far as we know, there's only one other service like this in SF, Laundry Locker, and they require the cooperation of your landlord because they install a pickup and delivery locker in your building. And they also limit their pickups to certain neighborhoods.