You probably know about the QuickLaunch toolbar for the taskbar (the bar that starts with the "start orb" and unsually ends with the time) at the bottom of your screen. There are other toolbars at your disposal as well. One I had not noticed before is the iTunes toolbar (of course you need iTunes installed to see this):

You can select it to be shown, but the application does not display the iTunes toolbar unless you have iTunes running and minmized. When minimized, instead of seeing it as a normal minimized application, this toolbar is activated instead which lets you do very basic operations in controlling the player as well as the ability to restore the full iTunes application to view.

You may be more familiar with the Windows Media player toolbar as they have offered this feature of a while now. It works in the same way (appears when running and minimized) but it offers quite a bit more than the track skipping, pausing and volume provided by iTunes. You can also see a mini-visualization and track information (plus it reflects your chose theme/skin).

There is also an "Address" toolbar that gives you a simple web browser address bar where you can quickly enter a web address. However, this is of fairly limited value today as you can also enter a URL in the search box in the start menu in the same way (I guess it saves you one click, and that is something).

Others include links, desktop and (again if supported) and a Tablet PC Input Panel. Right click your taskbar and select "Toolbars" to have a look at what options are there for you.