One of my favourite features on my own blog is On This Day. Here’s how to add it to your blog:

Visit GitHub - cleverdevil/micromemories to Add an “On This Day” feature to a website.

Micro Memories is known to work on all of the standard themes in If you are using a custom theme, you need to ensure that your theme makes proper use of microformats, especially the h-entry microformat. The open source themes are a good place to look for guidance.