Great addon, great to just kick out unwanted elements, still one thing is missing: One should get the chance to adjust the background color. I do print science website content frequently and there are always authors who publish their diagrams as .gif or .png with transparancy and white lines on dark background.
My workaround for the moment is to generate the print page, rightclick on the background and adjust the CSS backgroundcolor-tag to something appropriate like #444 with the developer tools, then print the document NOT with the addon but with the standard browser print function.

Hope one of the developers reads this, thanks!