Google customer reviews and seller ratings used to be just for Certified Stores. Now they are being rolled out to all Google merchants.
This addon presents customers with an opt-in form on checkout_success. Google follows up after delivery to ask for a review of the transaction.
Once you have collected enough reviews, you can show a badge with your seller rating.
Most of the addon is in a header_tags module suitable for use in several osCommerce versions. This supports the opt-in and showing the seller rating badge as an overlay.
You can choose on which pages the badge is displayed.
A content module for osc 2.3.4BS in other positions on the page is also provided.
The addon is also provided in a branch of Edge on github: