Demand Media, Associated Content and Examiner.com are each building up an arsenal of highly searchable “long tail” content. Now add Perfect Market to their ranks, a new company that seeks to provide the same “long tail” search optimized earnings capabilities to archival content from newspapers and other media.

The site just added a $6 million round lead by The Tribune Co. That adds to $15.6 million previously raised from Trinity Ventures, Rustic Canyon Partners and IdeaLab — each of which is also participating in the new round. The site originated with IdeaLab.

The company also announced an executive team that includes President and CEO Julie Schoenfeld; Chief Revenue Officer Tim Ruder, a longtime exec at Washington Post.com; and Chief Strategy Officer Rob Barrett, who was previously executive VP for Tribune Interactive and head of LATimes.com.

UPDATED: CSO Rob Barrett will be joining Examiner.com CEO Rick Blair and Associated Content President Luke Beatty on our “aggregators” panel at Marketplaces 2010

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