37signals.com blog has an excellent example of how social proof can be a conversion catalyst.  Am sharing their post snippet–

There’s a flash flood warning for all of Chicago today. Unfortunately there’s water in my basement (like other Chicago home owners)…

The flood fixing company U.S. Waterproofing has a cool feature on their website. Look at who we’ve helped in your neighborhood–

Back to my post …

See U.S. Waterproofing interface live– http://www.seepage.com/getreco.php?zip=60606

Now, U.S. Waterproofing is a Chicago based company so they are using their Google Map mashup to attract Chicago customers.  But you could do the same for your ecommerce business.  You could export a list of addresses shipped to in the last X years and create a Google Map mashup that places a pin over each shipped destination.  Then, shoppers could zoom in to see different locations in their state where other shoppers have bought your products.

Don’t think it’ll work?  A/B test it.  Don’t know how to A/B test?  Post a comment and I’ll help you out.