We’ve just launched the MODOA integration for Magento so you can connect your store to Google AdWords automatically.
You can easily launch each product on your store as an ad, and when you change the price or any other attribute, the ads will get updated automatically. When an item goes out of stock, the ad will be paused too.
You can request beta access for free at http://www.modoa.com/
There is an extension in Magento Connect as well.