Amazon’s Internet Movie Database (iMDb) is proving pretty popular on mobile devices. The company has revealed that its apps have notched up 40m downloads so far – split evenly between iOS and Android. According to TheNextWeb, IMDb’s apps and mobile site are currently bagging 150m visits a month, too. What’s just as interesting is how those apps are evolving: a new update has just added social check-ins so people can let friends know what they’re watching – big competition for apps like GetGlue. There are also more discovery features, and the ability to log in on Android using Amazon details.