While doing monogame tutorials, I’ve spent a lot of time on a simple thing that could be useful for someone else. The problem is the following – monogame framework can render xnb assets (images, sounds, fonts, etc), but it has no built in way to compile them yet. It looks like monogame team is working on its own implementation of content pipeline, but its not ready yet.
There is another open source gaming platform – cocos-2dx. In order to get his content builder you need a visual studio extension. So start visual studio 2012 extensions and updates, and search for cocos:
Now after you build project, it will generate xnb file per each asset added in the project. You can add those as linked files for other projects: