Recently I posted about a freeware, Hyperdock, that lets you use Windows 7 style taskbar thumbnails on Mac OS X. There are two built in features in Snow Leopard that do something similar to HyperDock, that is, let you switch between multiple windows of same application easily. These are Application Switcher and Expose.
You can easily browse through open application windows by using the Application Switcher. Just hold Command and use the tab to cycle through the open apps. You can easily activate Expose´ via a dock icon or keyboard shortcut.
However you probably don’t know that you can also simulate Windows 7 like taskbar thumbnails feature by using a combo of Application Switcher and Expose. Once the Application Switcher is active, press the up or down arrow key to activate Expose´, thus showing only the open windows for the application highlighted by Application Switcher. Its a really great time saver once you get used to it.