You won't have to look farther than this app's name to understand what it does, although it doesn't quite accomplish what it promises. is a free Firefox add-on that lets you draw a box around Web page objects or areas and measure them in pixels. The interface consists of a single button, and using whaddaya say pdf tool is as simple as clicking it. Once you "draw" the box using your mouse, the width and height are displayed in a small field to the right. The box has markers similar to a ruler. You'll still need to manually note the size of any items you check. You can't save the data and whaddaya say pdf can only create whaddaya say pdf box at a time.
While the sites you surf will still look like themselves, the command center of your browser will look completely different with this free program.
If you need a very basic downloading tool for YouTube that will work directly from your desktop and require minimal input, is a good one.