This is how you loop through different directories in Jekyll using Liquid. I searched through about 50 pages on Stack Overflow, NationBuilder, and GitHub. There should be better documentation on JekyllRB.com for this kind of stuff. You can change the page.layout to be anything in your page's front-matter (the stuff that starts and ends with the …

list pages in different directories

{% case page.layout %}
	{% when 'page' %}
		{% for page in site.pages %}
			{% if page.layout == 'page' %}
				{% if page.title != 'Home' %}
					<a href="{{ page.url }}">{{ page.title }}</a>
				{% endif %}
			{% endif %}
		{% endfor %}
	{% when 'app' %}
		{% for page in site.pages %}
			{% if page.layout == 'app' %}
				{% if page.title != 'Home' %}
					<a href="{{ page.url }}">{{ page.title }}</a>
				{% endif %}
			{% endif %}
		{% endfor %}
	{% when 'default' %}
		{% for page in site.pages %}
			{% if page.title != 'Home' %}
				<a href="{{ page.url }}">{{ page.title }}</a>
			{% endif %}
		{% endfor %}
	{% else %} 
{% endcase %}

Thank you so much for your work and for sharing it!

I wrote this years ago.
Does it still work?