There actually is a way to do this and it's probably the most often-used keyboard shortcut in my arsenal.
Simply type Windows + number, where number is a single digit, 1, 2, 3, ..., 9, 0. This allows you to access the first 10 applications that are currently sitting in your taskbar.
For example, I have Chrome pinned to the 1st location in my taskbar, so Windows + 1 always brings up Chrome. My favorite text editor (Vim will never die!) is tied to Windows + 2. And on down the line. I have the first 10 locations in my taskbar pinned so that I always know what a given Windows + number combination will bring up.
But more to the point, since the OP asked how to switch between multiple windows of the same application, here's where this keyboard shortcut gets really useful. To refine what I said earlier, Windows + number brings up the first instance of the application. But holding the Windows key brings up a list of windows of that application. (Similar to when you mouse over the grouped icons of an application in the taskbar.) Continuing to type Windows + number scrolls through that list.
For example, I earlier said I have Chrome tied to Windows + 1. More specifically, I always make sure that my gmail and calendar are in the first window of Chrome, so that Windows + 1 always jumps right to my email. But if I want to cycle through any of my other Chrome windows, I just keep the Windows pressed down and keep typing Windows + 1.
Another related and particularly useful variation of this is to add the Ctrl key. Windows + Ctrl + number brings up the last active window of the given application. This is very useful when you keep toggling back and forth between two different windows of the same application.
Please note that I'm using Windows 7, but according to http://windows.microsoft.com/en-us/windows-8/keyboard-shortcuts, these shortcuts also apply to Windows 8. That link also explains Shift and Alt key variations which you may also find useful, so I recommend taking a look at it.
And for the Windows 7 users out there, here's the link for those shortcuts: http://windows.microsoft.com/en-us/windows/keyboard-shortcuts#keyboard-shortcuts=windows-7