Denver-based TruEffect, the digital advertising firm, is continuing to build out its executive team, saying this morning that it has tapped Tim Mayer as its new Chief Marketing Officer. Mayer was previously VP of Marketing at ShopAtHome, and also served at Chief Strategy Officer at Trada, along with positions at Yahoo. TruEffect has been on an executive hiring spree in recent months, including hiring a new CEO in December, and ad operations head in November.