Google is going to extra lengths to make sure that you see its shopping links. The internet firm is introducing Shopping ads to image search results -- look for pictures of a nice couch and you may see a link to buy it. Google says this is largely about enabling more on-the-spot purchases, but there's no denying that this is partly about snubbing Amazon. After all, your first instinct may be to search Amazon when you spot that must-have item; you won't have to do that after today.