I have a testimonials page in my site but this does not bring more people in (I do hope it is at least useful to convince some visitors to take our migration to wordpress service but I have no proof about the increase in the conversion rate due to the list of testimonials).
Instead, what it is clearly good for the business is that some (happy) clients decided to write about their experience with your service on their own site. Not only because this is free publicity (I don’t have an affiliate program in place so they don´t get paid for that though they will have my eternal gratitude :-) ) but also because some of them may have a very popular site or a large number of followers so the impact of that post may be huge.
For instance, the last weeks I noticed a spike of traffic coming from Howard Owens’ blog. He is now my main source of referral traffic, even beating specialized wordpress sites like WPTavern or (in Spanish) Ayuda WordPress where our Drupal/Joomla/Whatever to WordPress service was featured.
After further investigation it turns out that Howard’s post ranks number one in google for the search “Migrating from Drupal to WordPress” one of the key searches for our service. Why is that I don’t know. I hardly doubt he optimized his site to rank high for this search :-) and the post is more than one year old but we all know that google is unpredictable.
The moral of the story is that it may be more important than you think to ask your clients to talk about their experience with your service on their own sites instead of just collecting testimonials to display on your site.