I don't know if this has been mentioned on here before, but I recently found an excellent & easy way to get your ebay shop listings lasted with google base. This means when someone searches for one of your products on Google it will appear at the top of the search in the shopping results section. It's called the Google Base Store Connector and you download it from here:-
http://base.google.com/base/storeconnector/index.html
I downloaded it a couple of weeks ago and business has increased by a third.