Google Shopping

Google base or merchant (originally called Froogle) lists your products on the Google Shopping search engine.

The google base feed that comes with opencart doesn't work fully as google has changed a number of its requirements - I recommend the extension by UKSB in the extensions store or one of the others available

Once you register with google merchant, use schedule a fetch to get the xml file the extension will give you the url for to automatically keep your products up to date.

You can also use the same feed to submit to The Find and other shopping search engines (also called shopping comparison sites).

http://screencast.com/t/nTzGvmouk