Monday, Google is equipping advertisers with a new tool to target specific Web sites with AdWords advertisements and is testing a new cost-per-thousand impression (CPM) bidding model that matches what advertisers are willing to pay with the cost of advertising on a specific Web site.

A limited beta feature of Google AdWords allows participating advertisers to place text, static and animated image advertisements on content relevant Web sites of their own choosing rather than to a general audience on the open Web. Animated banner advertisements are an addition to AdWords that launched last year.

A preliminary mock up Google's upcoming CPM bidding model provides more versatility than traditional CPM models, eschewing fixed costs and allowing customers to set their own maximum price while bidding in Google's auction. According to Google, the features will be integrated into the AdWords program within the coming weeks.

Summing up the causal effect of its new features, Google said, "By increasing competition for ad space on specific sites, we think that people who visit those sites will get more useful, more diverse, and more relevant ads."

Google recently opened up the AdWords API, or application program interface, to a subset of advertisers in hopes that such a move would rouse the birth of new concepts and software development to manage Google AdWords advertising campaigns.

The recent moves to impression-based advertising come as Google faces increasing pressure for its current cost-per-click model, which has be the subject of cheating and click fraud from some unscrupulous Web site owners.