—Forbes.com: Viacom exec Ty Ahmad-Taylor joins the business mag website in the new post, chief product officer. He reports to Jim Spanfeller, president/CEO of Forbes.com. He will oversee the site’s cross-platform efforts among Forbes.com and its sister sites, ForbesTraveler.com, ForbesAutos.com, Investopedia.com, RealClearPolitics.com, RealClearMarkets.com, RealClearSports.com and Clipmarks.com. At Viacom Networks, Ahmad-Taylor served as SVP, product development and strategy and worked on the MTV Networks (NYSE: VIA) family of sites.

—BusinessWeek: Sales exec Scott Miller has signed on as the company’s VP-digital media sales, reporting to SVP and worldwide publisher Jessica Sibley. Miller joins from Professional Social Networks, where he served as VP-sales. Release.

—Richrelevance: Renowned computer scientist Darren Vengroff has taken on a new role as richrelevance’s chief scientist. He’ll be leading tech strategy and development, as well as working closely with CEO David Selinger. Vengroff previously was CTO of and co-founded Pelago, a company best known for its Twitter mobile app, Whrrl. Earlier, he served as principal engineer at Amazon.com.

—Kontera: The in-text advertising solutions provider has appointed Hal Muchnick its new president, as well as promoted Bryan Everett to EVP. Most recently, Muchnick was EVP and GM of Operative and earlier, VP-global sales and account management for DoubleClick. Everett was Kontera’s SVP-sales for the past two years. Release.

—STACK Media: Karen Scott has been hired as director-digital marketing and ad solutions. She most recently was sales development director of Time Inc.‘s SPC Digital, and earlier held the same title at Time Inc. Interactive.

—Billabong: Surfwear brand Billabong has tapped Scott Wallace to lead digital content development as VP-new media and strategic partnerships. Before having joined the company eight years ago, he held a senior management role with sports management company IMG.

—Avista Capital Partners: Steven Marder joins the private equity firm as industry advisor, focusing on identifying digital media investments. Mardner co-founded Eurekester, a tech company for which he also serves as chairman, and co-founded search company SLI Systems, where he also serves as a director. Release.