This tool is great for sites that use lots of checkboxes like a registration form or your Hotmail or Yahoo! inbox. Imagine this: Your Hotmail inbox has 10 spam messages and you don't want to click on 10 separate checkboxes just to select them all. Now you can select them all just by drawing a box around them!
To begin drawing a box, your mouse must first be placed over one checkbox. Then drag to activate this tool.
Check out the video tutorial: