I have already posted a lot of addons which can be useful to you in IT manner. Here is an old post:-

Some Best Firefox Addons

Often we wait a lot for downloads to be finished and then to turn of computer, as while downloads we neither can surf nor we can use internet in any other mean as it will lower down your internet connection speed and download will take even more time. Similarly, at night you want to sleep but you wait for download to be finished so that you may turn of computer to save electricity rather then keeping in turned on till morning. So, is there any solution that your computer should turn off automatically after download has been finished? yes there is…!

Get the new addon of Mozilla Firefox – Auto Shutdown ng :-

Using this addon your computer will automatically turned off when your download has been finished in mozilla. You can get it here. Go to the page and then add it to Firefox.It also supports download from Downthemall firefox addon.

How to Use this Addon to turn of computer automatically:-

Once this addon is installed it will be shown up here in Tools>>Addons in mozilla browser.

Here you can see that options button is appearing in front of Auto Shutdown NG 0.5 click that and this dialog box will appear. Now, type there the command of shutdown according to your system, like I am at Windows so if you are also on Windows then follow me, do what I did in picture:- (Predefined Commands are also present according to OS being used just drop down “Predefined commands” and Choose OS)

• Shutdown Command For Windows:- %WinD%\system32\shutdown.exe
• Arguments: –s –t 0

Also specify the time for the dialog box to appear and notify for restarting computer after download is complete. I have chosen 30 seconds. So, whenever a download is finished following dialog box will appear and after 30 seconds computer will turn off.