Folica.com specializes in hair products. Their site has 100s of products and 1000s of reviews. How could we make reviews more persuasive? They should pick a popular product and for any customer that buys this item two weeks after purchase mail out two pre-stamped postcards requesting a handwritten testimonial. Scan these testimonials. Then run a split A/B test where one group of visitors see the old testimonial format and the other group sees the scanned handwritten format.
If conversion lift > cost of mailing out pre-stamped postcards expand the test to other product pages.