Did you know that IntelliCAD has robust AEC functionality? Architecture, Engineering, and Construction (AEC) is part of the ITC's BIM Special Interest Group, and there's a new, quick ITC tutorial available about drawing AEC entities in IntelliCAD.
Members of the BIM Special Interest Group are shipping IntelliCAD with the ability to draw and edit walls, windows, doors, stairs, and other AEC entities, all of which are compatible with ADT objects in other CAD programs. These members also have IntelliCAD functionality to directly import and export both IFC files and Autodesk® Revit® files, and then work with the content of those files. And like all things at the ITC, members not only have these features but also have open access to the source code.