AdBrite, a company that calls itself, “the internet’s ad marketplace,” already lets advertisers and publishers find each other directly through its site. Today, Adbrite is claiming to go further than other online ad services in matching an advertiser’s ad with a web publisher’s audience. It is launching a new service, called OTX, that lets third-party ad-targeting companies compete to serve the most relevant ads on publisher’s sites.

Third party targeting companies access Adbrite’s advertisement system via a live application programming interface, and bid for publishers. AdBrite is working with two ad-targeting companies to begin with: Personifi and Lucid Media (formerly Entrieva).

Many ad networks have their own, proprietary matching algorithms in place. San Francisco-based AdBrite’s hope is that its blend will serve more relevant ads, that lead to more click-throughs and so more revenue for publishers, its targeting partners, itself, and — assuming a site’s visitors care about its ads at the end of the day — advertisers.

There are many, many competing ad services that hope to optimize ads for sites. Most recently, we’ve covered the Rubicon Project, which just launched a program where it uses its own technology (and manual decision-making) to determine if a site is “high-quality.” Once certified by Rubicon, a site can run ads from multiple ad networks through Rubicon, with advertisers knowing — it hopes — that their ads reach the right audience.

AdBrite is a mid-sized competitor,with its ads reaching 85 million unique users in the U.S, according to web analytics service comScore.