Even though it’s a very app-centric world, it’s easy to forget that web apps are still around, and are still used by huge percentages of users. One reason for this is that web technologies continue to get more and more advanced, narrowing the gap between how people used to view web apps (easy to access, but lacking power and grace) and native apps (clean and easy to use, but limited to a specific computer).
As web apps get more and more powerful, it is easier to lose track of new features, and to navigate the apps in a quick and efficient manner. Thankfully, some web app developers have built-in a handy dandy shortcut to show the many keyboard shortcuts for navigating the more powerful, complicated web apps:
Shift - ?
Here are a few examples of what you see when you hit ‘Shift – ?’ in popular web apps:
Facebook: 
Gmail: 
Twitter: 
So, if you are a frequent user of any of these web apps, give ‘Shift – ?’ a try. I can almost guarantee that you will learn not only keyboard shortcuts that you didn’t know existed, but also likely full features or capabilities that you didn’t know were there.