Windows Vista ships with a really nice feature built into Windows Explorer which is folder breadcrumbs. By simply clicking on a folder in the navigation path, you are instantly jumped back to this location. To add this functionality to older versions of Windows, try the free Explorer Breadcrumbs tool.

Not much to explain here as the usage is really self explanatory and there is an image available on their page which illustrates exactly how the tool works.

While this program is free to install and use, the author asks that you donate a small amount to encourage the development of the program. So if you find it useful, help them out.