GaiaEHR(Electronic Health Records) is a Open source Web-Based Software for:
Medic Practice management
Electronic Medical Records
Prescription writing and medical billing application
And it can be installed on the following systems:
Unix-like systems (Linux, UNIX, and BSD systems)
Mac OS X
And other platforms that can run Apache Web server, MySQL
We have some other projects here in GaiaEHR.org, some private and other are GPL'd.
Great! super easy to use and love the user interface.