While it would be nice to have unlimited access to a T1 connection for huge downloads (here's looking at you, World of Warcraft patches), that's just not the case for a majority of users today. We can't all download Linux builds at our work computers. Sometimes, one just has to grin and bear it--"it" being the act of leaving one's computer on overnight for a furious session of non-peak-hour downloading.
Here's the problem: When said download finishes sometime in the wee hours of the night, your computer stays on. That might not be the biggest deal in the world for a single session or two, but suppose you're a mega-downloader. Suppose you're the kind of guy or gal who's always grabbing new files, new updates, new builds of this and that--in short, you're the reason Comcast invented service limitations. Well, it wouldn't be in your best interest to leave your computer on all the time. Computers are noisy. Computers use power. Computers produce heat.
Thus enters this week's Firefox add-on of the week: Auto Shutdown. As the name implies, this quick little addition to your Firefox browser adds some critical functionality to your downloads, be they through Firefox's built-in download manager or the popular add-on DownThemAll.