Pearl Crescent Page Saver for firefox

Page Saver lets you capture images of web pages, including Flash content. A web page screenshot can be saved in PNG or JPEG format. Using Page Saver, you can capture an entire page or just the visible portion. To allow you to control the image capture process, a wide variety of options are provided including a file name pattern and an image scale setting (e.g., save at 50% of original size).
Images may be captured using a toolbar button, the browser context menu, or from the command line.

Add to Firefox
https://addons.mozilla.org/en-US/firefox/addon/10367

A Pro edition of Page Saver is available that adds features such as file upload, extensive command line options, and the capability to select a region on the page. For more information
visit http://pearlcrescent.com/products/pagesaver/pro/