I recently bought a new monitor, a Samsung SyncMaster 757p, and I'm trying make good use of its USB interface. The software provided by the manufacturer is of course for Windows only, and as far as I know there are no open-source tools for this purpose. So far I've managed to retrieve all the useful information from the monitor, but not to change settings.
The USB monitor specs are available here.
The code I wrote is available here. Disclaimer: it is ugly, incomplete and probably broken in countless ways as it is my first attempt at this kind of hacking. Use at your own risk.