Now, Google Desktop 5 might have been discontinued, back in September of 2011, but millions of people used this handy little search tool, so it is still available to download. This program will only work if you have Windows Vista or XP, but it allows you to quickly search your computer, and the internet, through the power of Google.
It's pretty quick to set up and it even comes with its own sidebar. Now, this will replace your Windows Vista sidebar, but you can add extra things to it, like your Gmail contact list or a Google search bar. The sidebar looks just as sleek as the Windows version, and there are quite a few different options, so it might be worth swapping sidebars.
But you don't even have to use the sidebar; you can opt for the "Floating Deskbar" or just have it as a notification icon on your Taskbar. The Floating Deskbar is a really simple looking search box, which you can move to anywhere on your screen to use Google Desktop's main function: searching for things. Double-clicking the Taskbar icon will bring up a more visually appealing search box, but you can't move it and it sits in the center of your screen, plus it disappears when you go to do something else.
Now, operating systems have come a long way, so I could see a lot of people really not seeing the point in using Google Desktop. But if you prefer Google's products over Microsoft's products then you might want to swap sidebars and use Google's indexing, instead of running your search indexing through Windows. So, if you're really a fan of Google then this might be for you, but its relevance might have gone the way of 8-track tapes. Sure, it's free software, but there won't be any new versions and it probably won't work with newer operating systems, or even newer browsers.
I can't see a use for it myself, but if might have been really handy in the past. Feel free to check it out if you'd like; perhaps you'll find a good use for it.