Considering the popularity of both online forums and product reviews, it makes sense that customers ask and answer questions of each other about a product right on the product page. Shoes.com provides Q&A for every product it carries.
To encourage participation, Shoes.com requests it in a post-purchase email. The questions in the email are specific to the product and based on what would be most helpful to a shoe-buyer: "Do they run wide or small?" or "Are these heels formal enough for the prom?"
Another shoe site, Shoeline.com has a feedback mechanism called the Return-O-Meter, so prospective buyers can see why people returned an item - it fit short, it fit long etc. But Shoes.com's approach covers the "long tail" of questions in consumers' minds - and gives them an outlet to resolve them.
The concern with this type of user-generated product information is what you typically see on blogs and forums - spam comments, comments that are not useful, inflammatory comments about other members and so on. So proceed with caution, and make sure you have a dedicated team member moderating the conversation.
Another caveat is if nobody answers customers' questions, or the answers are not helpful. Shoes.com has its representatives provide input (indicated with a badge) for most questions. Unfortunately I found several questions while surfing the site that have gone unanswered in over a month.
The big challenge is to get people taking the time to contribute. To encourage repeat participation, Shoes.com could implement a system reward top contributors with gift certificates or a chance at a prize draw, for example.
What do you think are the pros and cons of having social questions and answers?