We do have testimonials on our own site, but we prefer to use places like BBB and 3rd party services that allow users to rate/comment on us, and doesn't allow us the ability to EDIT their comment. Anyone can put words in someone elses mouth and say "bobby said". We're involved with a number of partners that review our services and members of those softwares put direct reviews on THOSE sites to us.
Also, any of our customers that want to provide a testimonial, we prefer them to put the testimonial on THEIR site, and we'll link to it. This gives credability also. We can capture a portion of it on our site, but a link to their actual statement is much better.
Also, HostingAssured used to allows people to post a review, they run checks on the domain to make sure it's actaully hosting with the host they are giving positive (or negative) reviews for. The post can not be edited by the host, but the host CAN provide comments. I see their site is no longer active - it's a shame. It was run by FindMyHosting.