Are there any plugins for ImageFlow.NET that enables me to auto crop images to focus on objects, not faces, in them? Or any other non-plugin way to do it with ImageFlow.NET?
Not yet, but it is something we're planning to add. In the meantime, you could try using https://github.com/softawaregmbh/smartcrop.net to get the crop coordinates then feeding them to Imageflow. It looks like a slow library, and the built-in encoding and resizing is very poor, but if you only use it to get coordinates you should be fine.