I'd throw in a whole-hearted vote for Lily's Carpet Cleaning. A local independent team we came across that uses non-toxic soap and plain old elbow-grease to clean your carpets. I'm sure you can find more reviews of them online, but they are fast, inexpensive and really friendly. We've only had an 8x10 oriental rug done but it came out great and we've had them back several times.
http://lilyshomeservices.org/
Here are some yelp reviews: http://www.yelp.com/biz/lilys-correct-carpet-and-oriental-rug-cleaning-boston
Lily's Carpet Cleaning
Date: 2010-02-09 12:34 am (UTC)http://lilyshomeservices.org/
Here are some yelp reviews: http://www.yelp.com/biz/lilys-correct-carpet-and-oriental-rug-cleaning-boston