i would like to see ShareYourCart added to marketpress to allow owners the ability to automatically offer discounts when the customer shares their product on their facebook or twitter.
It is already integrated with magento, getshopped.org(wp ecommerce), cubecart, wp eshop, thecartpress, prestashop, wp storecart, wp estore, woocommerce, oscommerce.
I think it would a valuable asset to marketpress.
It would need to be integrated so the shopping cart would display a button below the checkout button. to get a discount they would have to click that button, and it would then share to fb or twitter, once shared, would return to the shopping cart and apply the discount automatically, but also give the owner of the marketpress the option to have it email the person a coupon for the discount.
Info for integration is at http://developers.shareyourcart.com/1-hour-wordpress-integration/