When ETFs began to make their way into the investing mainstream, almost all products were “plain vanilla” funds linked to well known stock benchmarks, such as the Dow Jones Industrial Average and S&P 500. But as the popularity of ETFs has surged, so too has the number of product offerings, with approximately 30 issuers now [...] Related Stories: Five Twists On S&P 500 ETFs Beyond SPY: Five Outperforming Large Cap ETFs Three ETF Alternatives To UNG