Right click on any web page, frame or iframe, click "Save Page As Image..." and then resize the selection around the piece you want to save. The element that you right clicked on will automatically be selected, you can quickly expand the selection to the entire page by double clicking, to restore, double click again. This add-on is entirely open source, contributions are welcome at the github.

Capture an page or just a specific region. Adds a right click option to take screen shots of an entire web page or just part of a web page to save as an image.