This question is tricky to answer.
In general there's no restriction to the "supported mimetype" since you can configure as many different mimetypes as you want, including your own. You can look at the DataModel/config/alfresco/mimetype/mimetype-map.xml and mimetype-map-openoffice.xml to get an idea of some of the values, its a long list.
On the other hand clearly some mimetypes have more features enabled e.g. can the mimetype be previewed, indexed, transformed. Again that is configurable so in theory that's unlimited as well.