Windows 7: Free utility Taskbar Items Pinner adds pre-defined or user-defined folders, files and even web pages to the Windows 7 taskbar.
Adding one of the pre-defined folders (like, say, your Recycle Bin) is easy enough: Just run the app and tick the checkbox next to the folder. Adding other folders, files or web apps requires a little more work but is still pretty simple. Browse to the path of the item you want to pin, add an app icon (as FreewareGenius points out, you actually have to choose your icon for everything you pin, which is a little annoying), and click the big Add Item button.
We've detailed a software-free method to pin any item to the Windows taskbar that requires a little more work, but this is a nice alternative.
Taskbar Items Pinner is a free download for Windows 7 only.