Jekyll-Plugins is a project mainly written in Ruby, it's free.
Jekyll Plugin
This one is intended for use with my fork of Jekyll. The goal of this fork is to keep content files/images in a separate folder. That way, this folder can be shared as a dropbox folder with the client, and they'll have an admin-less CMS.
This plugin solves the problem of having template-related static files (logos, icons, etc) outside the _content folder.
Put in _plugins folder
use order: (number) in the YAML section of the pages
loop over site.sorted_pages to build your menu