OSM Categories embed an OpenStreetMap map to your page by using the OpenLayer API. For every category in your blog a differnt layer on your map show markers for every article with an geotag.
You just have to save the lon and lan parameters in a custom field. It’s possible to use different marker images for every category.

In your page just insert the shortcode: [osm-cats]

Open the plugin settings page for basic settings like:

map dimensions
map center point
initial zoom faktor
exclude categories
article custom field for marker lon and lat parameters
marker popup content
marker images path

It’s still BETA so please send me feedback and your ideas! Thanx a lot.