Google is testing a search service that will access “Deep Web” content, providing searchers with free previews of restricted or subscription content, reports BetaNews (via paidcontent). The service is being tested with a few sites, which are under confidentiality agreements, but apparently one of them is singing like a canary. “Premium content will be indexed and tagged as paid, and will be displayed in a special content area on the right side of Google’s search results, underneath the AdSense advertising links,” according to the report.