It doesn't seem that the Google monopoly is so bad for consumers since they have Bing, Yahoo! and other sources of information. The Google monopoly is bad for businesses, advertisers. If you are in Europe and selling things via the web you'd have a very hard time getting started and really making it by being able to target only 5% of your target market if the bids were to high or you couldn't advertise on Google for whatever reason.
It seems like the only real way to stop the spread of domination might be to limit the acquisitions Google can make but there never seems to be any real analysis of how the acquisitions they make will affect the advertising market or the consumer. Has any acquisition of theirs ever been turned down?