turn.bmpTurn, a San Mateo, Calif. company that delivers advertising tailored for Web sites, depending on their readership and other variables, said it has raised $8 million in second round financing.

Turn was launched by Jim Barnett, the former chief executive of once-popular search engine Altavista. We wrote about Turn last year after it rose $18 million. Since Turn launched, other ad network companies have emerged to bring about more targeted ads for Web sites, while others have been acquired. Turn uses numerous variables to select advertising for a site, such as a site’s subject matter, its design, and its owners’ preference for click-through versus impressions.

Norwest Venture Partners, Trident Capital and Shasta Ventures are among the investors in the latest round, according the regulatory filing about the financing cited by PEHub. However, regulatory filings are notoriously unreliable. A lead investor hasn’t been named.