OpenEMR is a Free and Open Source electronic health records and medical practice management application. It is ONC modular "Meaningful Use" certified and it features fully integrated electronic health records, practice management, scheduling, electronic billing, internationalization, free support, a vibrant community, and a whole lot more. It can run on Windows, Linux, Mac OS X, and many other platforms. This project is based at sourceforge: http://sourceforge.net/projects/openemr/