There are literally millions of Android apps to choose from, but if you're looking to go beyond what Google Play has to offer then you're in luck. Thanks to a recent update, you can run Windows 7 apps on Android using a program called Wine 3.0.
Use Wine 3.0 to get the classic shooter Quake II on your Android device (Souce: Steam)
Wine has actually been around since 1993, making it possible to run Windows software on Apple hardware and Linux-powered computers. With its latest update, that same feature is expanding to Android, though there are some limitations to what it can do.
Android Police notes that Wine 3.0 is a little unstable. It seems to run best on newer devices, but it may crash older phones or tablets. It also runs everything in full screen, so don't think you'll be running two programs side-by-side like you would on an actual PC.
Additionally, Wine 3.0 runs better on x86 Android devices (meaning the processor is based on Intel technology). That means if you have an ARM-based device you'll be limited to using programs that work with Windows RT. Even with those limitations, Wine 3.0 still opens up some interesting possibilities.
If you're into gaming, you can use Wine 3.0 to get classic first-person-shooter Quake and its sequel, Quake II, running on any Android device. If you're running an x86 chip, you could also try launching the full version of Steam (instead of the limited mobile app) for even more video games.
Not a gamer? Try Greenshot, an advanced screenshotting program for Windows that let's you instantly annotate your images, print them, or share them in an email.
That's just a quick sampling of what's available. You can check out the full list from XDA-Developers for even more Windows apps to run on Android with Wine 3.0.