Anybody wanting to implement Revit MEP seems to know that content creation is a must. What you may not know is that Autodesk has posted a real good introduction to making MEP families. Not doors and windows but actual mechanical and Electrical components. Go to Autodesk's Revit MEP Documentation webpage then make sure to scroll to the bottom of the page, where you will see this.
Down load today and get busy making your own family.