rfcview.el is a groovy mode for viewing RFC documents, created by NeilVanDyke. It fontifies headings, and hides the header and footers (which are designed for a line printer), to improve on-screen readability.
Get it from the author at
On a Debian system see DebianPackage:emacs-goodies-el.
There’s a significantly enhanced version at http://www.loveshack.ukfsn.org/emacs/rfcview.el (which was contributed back but hasn’t been used).