The 'Peg It' button lets you easily add images from any website you are surfing.
Drag this button to your Bookmarks Toolbar
To install this button on Firefox:
Display your Bookmarks Toolbar by clicking View > Toolbars > Bookmarks Toolbar. Drag the 'Peg It' button to your bookmark toolbar. When you see an image you want to add to your boards, click the 'Peg It' button!