Chrome: Google's web version of the Play Store is handy, but it's still missing a few features after all these years. Toolbox for Google Play Store helps fix a lot of minor issues to make it easier to use your apps.
Toolbox, created by the site Android Police, offers a ton of handy tweaks. Most notably, in addition to the Install button, you'll also see a button for APK Mirror. This site (which is also owned by Android Police) hosts APKs for apps that may not be uploaded yet. This is particularly handy if you're sideloading an app that hasn't rolled out to everyone yet. You'll also see buttons for AppBrain (an alternative way to explore the Play Store) and Android Police's coverage for that app, if any exist.
The extension will also show you if there's a beta version of an app available. Many companies run beta programs for their apps to test out new features before they roll out to everyone, but you have to find them on your own. This extension will now show you a handy link where you can sign up for the beta and download the most bleeding edge version immediately.
Best of all, you can turn off any feature of Toolbox individually. So, if you don't know or care what AppBrain is, you can disable that button in the extension's options. For now the extension is pretty bare bones, but the few features it does have are pretty handy.