If you want to use the keyboard to switch from one Windows 7 application to another then you could press Alt+Tab repeatedly, cycling through all your programs until you reach the one you need.
But it could be easier to access it directly. And so if you see that Outlook’s taskbar icon is 8th from the left, say, all you have to do is hold down the Windows key, press 8 and it’ll immediately jump to the foreground (or launch, if it’s a pinned shortcut).
Of course if your taskbar is cluttered then it may take a moment to figure out exactly what number any particular icon might be. But that’s where the free 7 Taskbar Numberer comes in. Launch its single tiny executable and it’ll add numbers to each of your taskbar and system tray icons, so you can identify the one you need at a glance.
The end result isn’t particularly pretty, but it works and it’s very easy to use. RAM use is fairly minimal at 2.6MB or so, and if you decide you don’t need the program any more then right-clicking its system tray icon will unload it, and so remove the numbers, right away.
One small annoyance here is that the program displays a small status window every time it’s launched. If you set up 7 Taskbar Numberer to start along with Windows, however, this turns out to be easy to fix: just add a -hidewnd switch to the shortcut. (Check the program Readme.txt file for more.)
Otherwise, though (and putting aside the horrible program name), 7 Taskbar Numberer is a small and simple tool which can make it easier to switch to and launch applications on your taskbar. It’s also entirely free of toolbars, adware and any other common freeware hassles, so if you’re at all interested in the idea then you can download and try the program without fear of any unexpected consequences.