A page with a list of contacts who post messages on twitter (tweet) about engineering better customer experiences, customer advocacy, customer value. Etc., etc. you get the point ;-D
This research paper looks at the different types of testimonials that customers or service users can provide your organisation: to persuade and shape behaviour.
You can also extend this to your other stakeholders.
Very academic so you have to sift through it with patience and get the nuggets out.