Expand the YouTube Video Player to its Maximum Size :- The default full screen button in the YouTube video player expands the video such that it covers your entire desktop area and all existing windows on the screen stay hidden as long as you are watching the video is this "maximized" state. That’s one way of doing things but what if you want more control over the size of the YouTube video player, here’s a simple hack – just replace the word "watch" in the URL of any YouTube video with "watch_popup" and the video will expand to fit your browser window, not the desktop.  For instance, if the original YouTube video is located at

youtube.com/watch?v=2mrRvUNlq50  the same video can be accessed standalone outside the YouTube 

websiteyoutube.com/watch_popup?v=2mrRvUNlq50Know if your neighbours are stealing your WiFi connection

                        Just follow the steps:-

Open your browser and visithttp://192.168.1.1 orhttp://192.168.0.1  depending on your routerFind the tab that mentions “Attached Devices” or something similar.Find the computer name, IP address and MAC Address (sometimes called Physical Address or Hardware Address) of your computer using ipconfig commandCompare it with those displayed by your router in Step 2. If you notice some strange devices, then your neighbor has been sneaking in on your internet connection and it is best to add a password.                 

  Navigating between fields in form : We are all very familiar   with [ Tab ] to move to next filed while filling a form but what if you want to go to previous field on the form there is simple shortcut for this [shift]+[tab] , which will put cursor on the previous fieldSuppose you wan to make all your windows transparent to see the gadgets on desktop use [Windows] + [Spacebar]Working on multiple monitors : there is a easy way to move selected window to different monitor without using mouse [Windows] + [SHIFT] + right arrow OR [Windows] + [SHIFT] + left arrow Move selected window from one monitor to another. They will remain in the same relative location

Another on i wont call this as useful  but can be fun :

Watch ASCII Star Wars in Windows XP, Vista, 7, 8 & 10

There is a complete copy of Star Wars done entirely in ASCII characters that you can watch in the windows operating system (or any OS that supports telnet)

Note : Telnet is turned off by default in the latest versions of Windows. So, in order to watch star wars, you must first enable telnet by going to Control Panel › Programs › Turn Windows Feature On or Off and ticking both the telnet check boxes.

After doing that, follow the steps given below:-

Go to Start, Search in Windows Vista and Windows 7 and Windows 10. On Windows 8 and Windows 8.1, open the main Start page.Type telnet and press Enter.In the following command prompt window, type "o" without quotes and press Enter.Now type "http://towel.blinkenlights.nl"  without the quotes and press Enter.

If you do not need telnet anymore, you can turn it off.