A custom tag for the Liquid templating engine (and therefore Jekyll) that allows you to iterate over files in a directory, using a glob pattern (see Dir.glob). This snippet barely qualifies for it's own repository but I'm including it for completeness.
If you're using Jekyll you can simply clone this repository into your _plugins folder to begin using it, otherwise place it somewhere where it will be read by your application.
A usage example:
<ul>
{% glob images/*_slider.jpg %}
{% for file in files %}
<li><img src="{{ file }}" /></li>
{% endfor %}
{% endglob %}
</ul>