Because you are replacing the switch, not installing a new switch, you can get away without a ground. You should install a nonconducting, noncombustible faceplate though.

NEC 2008
404.9 (B) Exception. Where no means exists within the snapswitch enclosure for connecting to the equipment grounding conductor or where the wiring method does not include or provide an equipment grounding conductor, a snap switch without a connection to an equipment grounding conductor shall be permitted for replacement purposes only. A snap switch wired under the provisions of this exception and located within reach of earth, grade, conducting floors, or other conducting surfaces shall be provided with a faceplate of nonconducting, noncombustible material or shall be protected by a ground-fault circuit interrupter.

If you were installing a new switch, you would be required to provide an equipment grounding conductor at the outlet. And the switch would have to be properly grounded, in accordance with the National Electrical Code (NEC).

There was a time when an equipment grounding conductor was not required at each outlet, so it's fairly common to come across this situation (especially when working in older homes). You'll often see exceptions like this written into codes, so as not to require a full rewire just to replace a switch.

New info, Better answer

If you are replacing a switch a ground is not required, as per the above exception. However, if you're installing a switch; replacement or otherwise, into a metal box that is grounded. The switch will be ground via the devices yoke and mounting screws. So if the metal box is grounded, the switch is also grounded.

If the box is nonmetallic, and there are other grounded devices within the same enclosure. You can ground the new switch using a jumper between the switches grounding screw, and the other devices grounding screw. Just keep in mind, that you can't terminate two conductors under a single screw terminal. So if you do this, you'll have to use pigtails to make the connection between the devices.

The MA-FQ4M dimmer doesn't dim its output directly -- it's designed to communicate over the powerline with a compatible canopy module instead, which is why it didn't dim your chandelier. It shouldn't cause your fan to hum when used with the proper canopy module, though -- I'd suspect that your real problem is with the fan itself (perhaps the windings are slightly loose inside the fan motor or something like that).

As to why the fan didn't work with a single pole switch, I suspect it's because the canopy module wasn't seeing the right signals to turn the fan on. Either that, or you simply goofed when you wired the switch.