While it is possible to purchase "automatic" fan controllers, you'll have to spend a good bit to get one you'll be happy with, especially for a large number of fans. There are quite a few fans made with automatic thermally-controlled speeds all built in to the fan itself. The problem with these it seems is that intake fans will be receiving and sensing the coldest temperatures, and therefore will not run at full speed unless measures are taken to place the sensors in a hotter area of the computer, and even then results can be disappointing. The same problem exists for exhaust fans, but in reverse....they don't ever slow down.
As for fanbus controllers, the DigitalDoc series has a good reputation, and it will monitor 8 devices, but I don't believe that it controls the fan speeds, just turns them on and off, depending on pre-set temperatures being reached. They are however a good source of temperature and fan speed information. It also has a "Force" function to override the temperature activation.
One solution would be to have a set of fans controlled "automatically" by the fanbus of your liking (Or the one included with your case), and have a second controller that is manual, either incrementally adjustable via potentiometers, or just simple switches from 7V to 12V or off.
Perhaps the best solution, and one of the simplest, is to use a monitoring program such as Motherboard Monitor, or included with your Asus board, AsusProbe to monitor the critical temps and fan speeds. Run the sensor wire of each fan to their respective motherboard headers, and run the power leads to a simple rheobus. These come typically in either 4 or 6 channel, and you may turn all the fans down until you're satisfied with the sound level, check the temps and if they're acceptable, leave it there. Turn them on max for gaming and overclocking. The main advantage to these simpler controllers is that you can run more than one fan per channel and at just about any speed desired. Check the watt ratings per channel though. Your mileage may vary. ;)