Well after searching the forum for a while, I thought that having a thread specifically for discussing the best fan controller for our application might be in order..

It seems as if the following fan controller may work very well, as they have thermal sensors, and can display up to four fan speed and temp, along with some temp warnings.

CoolerMaster Aerogate II or Aerogate III

Aerocool Gatewatch.

There are plenty of other ones, and I think it would be great if everyone using one would put in their recommandation.

Finding one that controls the fan's rpm according to the temp may be a good idea also.

Let's start the hunt!!

I bought a fan controller for my PJ, but after fiddling with it for a while, I decided to use the KISS method. I went and got an attic thermostat from Lowes for $14 and it works perfectly.

The major problem with most fan controllers is they never turn the fan completly off, and the lowest RPM is usually 50% of max RPM.
SO! If you want to be able to have your fans run for a while after your lamp goes out you will have to put them on separate circuits. Unless you want to unplug / swich off your fan controller, your fans will run at 50% of their max all the time no matter what the temp is inside the projector (While the lamp is off).

VANTEC NEXUS NXP-201 FAN CONTROLLER is one of the best fan controllers on the PC market.

it's not very appropriate for PJ use though.

I had an Akasa AK FC-06SL Fan Controller but it went up in smoke (literally) a few days ago. I couldn't return it because I had cut the connectors off and soldered the wires together. A mate said he has heard that running a fan at too low a speed can cause speed controllers to overheat, which is a bit worrying because I have a second fan ready to be installed and I was going to run them both at minimum speed. Can anyone confirm or deny this?

As a replacement, I have an Enermax UC-A3FATR2 Multifunctional Panel coming tomorrow, which can control two fans, has two temperature probes, and an adjustable maximum temperature alarm.