I’ve developed a simple plugin to add extra common media types (like MsOffice, OpenOffice, PDF etc.) to the fallback thumbnails images available for Omeka Classic; the plugin can replace default images (video, text and image) too.
Please note: to be able to change standard fallback file image too, for the moment being one needs to tweak one core file (see New fallbackImage not showing up thread for more details). For all other images, there’s no need to tweak anything.
The plugin is available on GitHub, at https://github.com/DBinaghi/plugin-MoreMediaTypes
As always, comments, suggestions and improvements are more than welcome.