Lisp:stripes.el previously published to gnu.emacs.sources, Message-ID: <bo186d$16q88d$> by MichaelSchierl.

  ;;; Commentary:
  ;; highlights every even line with an alternative background
  ;; color. Useful for buffers that display lists of any kind - as a
  ;; guide for your eyes to follow these lines.
  ;; when invoked with a numeric prefix arg, color that many lines
  ;; instead of every other line.
  ;; Put this file into your load path,
  ;; (require 'stripes) and do a (turn-on-stripes-mode)
  ;;  whenever you need this (e.g. in hooks).

Only slightly related: Library printing.el (PrintingPackage) lets you print a buffer with zebra striping (alternating colors as described above) as an option. Library printing.el (PrintingPackage) is available from ViniciusJoseLatorre. – DrewAdams