While we wait for the option to save a web page as a PDF, due by Firefox 3 final release, there is another option for sharing and archiving web pages. Save As Image, is a simple yet useful Firefox extension developed by Rowan Lewis that adds an option to Save Page as Image to the File menu.
When you select it you have the option to select a particular area of it and tweak it manually with dedicated text boxes provided. At least in theory. The selection overlay that should appear over the actual web page image, appears below it which makes it useless. I’ve contacted Rowan on this and hopefully he will take some time to either fix it or remove the selection features and make it a simpler save-whole-page extension.
With options to choose the image format (JPG/PNG) and image quality I find it extremely useful and, even with the image large size (specially when saving as PNG), still a better alternative to HTML versions that I would like to see available by default in Firefox as another option in the Save Page As… dialog. Being only 10KB (including the user interface) it shouldn’t be a big overhead. Options to save several tabs in a single animated PNG (which will be enormous) and a grayscale would be great to have as well.
Get it at Mozilla Add-ons