Google share + coupon
this is PrestaShop module that adds special button to your product pages.
This button allows to share product on google+ timeline
after sharing customer can receive unique dedicated voucher code
more informations about module you can get here:Google share + coupon
You can find there only valuable solutions for your e-commerce shop based on PrestaShop engine. Search the best plugin for your store that will meet your requirements and just use it.