While text-only emails can be effective enough for welcome emails and onboarding campaigns, some sites may want something a bit more visually appealing--but without spending a lot of dough. StockTwit does just that with this elegant two-color (gray and green) design with simple graphics that's sure to engage site users. And since we logged in using a Twitter account (@SubSiteCentral), there's no need to repeat user ID or password info!...