Real answers:
http://cutycapt.sourceforge.net/
http://iecapt.sourceforge.net/
http://www.websitescreenshots.com/
http://www.princexml.com/
http://khtml2png.sourceforge.net/
http://linkpeek.com/
https://htmlcsstoimage.com/ (Uses Google Chrome)
https://gofullpage.com/ – Full Page Screen Capture (Chrome extension) – see this superuser answer for more info
(Don’t know of one to use Mozilla’s renderer, though.)