Karten was a WordPress plugin to plot Instagram photos on a Google Maps map. The plugin would go find all geo-tagged Instagram photos relating to desired user(s), hashtag, date range, start/end date, and/or maximum number of posts and plot them on a Google Map.
I came about this idea while preparing for a move to Colorado. My father and I were planning to tow my car across a portion of the country and wanted to let people follow along on our journey. The result was what became Karten.
You could use Karten in any post/page content using the shortcode. Additionally, you could use the theme hook to add a map outside of the content in a theme template.
Karten is open source and released under the GPL 2 license, but is currently deprecated. It lives on Github, so feel free to fork it.