I tend to remain sceptical of anyone making claims without valid and reliable data. With that said, some practices you list are of critical importance; others, I'm not sold on one bit. Please don't take this a slight against you, but rather as a criticism of your general claims (and lack of scientific data therein). Moreover, if you enacted all those changes at once, you'll never know which one made a real difference, and which one did absolutely nothing. Proper scientific methodology calls for the manipulation of one variable against a control (unless you want to run the more complex ANOVA).
Clean your MacBook Pro fans from within... it's simple, open the
bottom closure and blow the hell out of these fans
Absolutely. This is by far the most effective way to ensure your system continues to operate nominally over the years. It is sadly also the most neglected. Dust sticks to the blades (and most of the internals) creating a "sticky" residue and not only prevents the fan's blades from spinning at their optimum, but seriously restricts air flow. Computers generally accumulate far more dust than people expect. Regular cleanings are essential!
Download and install Fan Control and run your fans @ 2800-3000 RPM
This of courses comes at a sacrifice to noise (increasing it) and I'd like to see data on how much cooler the chips operate with such a small increase to RPM.
Ditch all browsers to Safari, I tried them all Firefox up to version 5
and 7 (Aurora), Chrome and Opera... nothing beats the CPU usage (less
of it) than Safari. Also flash youtube videos run with less resources
on Safari for some reason
Again, I'd like to see some data being this claim. These guys have conducted some very loose tests that support your assertion, and I'm inclined to agree that Safari, being so tightly integrated into OS X should net improvements over its competitors across the board, but a few CPU cycles here and there aren't going to amount to a drop (drastic or modest) in temperatures (these saw extremely small differences in performance).
Use your faster GPU on AC Power, and lower on Battery power (use
http://codykrieger.com/gfxCardStatus for source-based GPU switching)
GPUs put off heat, wether they're integrated or discrete. I can see a reduction in power, but a reduction in heat, again, I'm not sold. In the case of MBP, models that possess discrete video cards have dual fans (one for the CPU and one for the GPU). So using the discrete card may kick off additional heat, but it's also got a dedicated fan to push that heat away from the machine. Stressing the integrated chip will see the CPU spike in temperatures, which means that fan will be doing more work to handle the additional load. It may be the case that the fan on the CPU (together with the integrated GPU) may be sufficient in pulling away the excess heat, but at no doubt the cost of excessive noise (generated by 6,000 RPMs). I don't know if anyone has done testing, but from my own anecdotal experience with my old MBP1,1, the GPU fans rarely switched gears (unless playing intensive games and then the issue would be moot as you'd want to use the discrete video). It was always the CPUs fans that took the brunt of the work.
Replace your internal hard drive with an SSD
Not only will this greatly improve performance, but it can't hurt in reducing temperatures. The idle/active power consumption of an SSD is about 0.5W to 2w, respectively. The average power consumption of a traditional HDD is about double that (1W to 2.5W, respectively). I won't know what that transfers to in the temperatures department, but it certainly can't hurt.
Keep your monitor running @ 90% brightness and keep your keyboard lights off or low
I'd love to see data on this. LED backlighting is already quite efficient and distributing heat, but I'm not sure a reduction (at least that small) in power would have any effect. As for the keyboard lights, those are LEDs and as is with such small LED bulbs, they are incredibly power efficient and produce little to no heat as a result.
With all that said, I'd saying re-application of Arctic Silver 5 (or thermal compound of equal quality) and the cleaning of dust from the internals is the most effective (and proven) way to keep your system cool. I've never seen data to convince me that turning off some service, or placing your system on a pad with a couple of fans does anything (other than perhaps keep the case cooler to the touch) worth merit.
Best Answer
I would not recommend changing you fan-speed management if you are not sure about it. 38°C - 49°C won't harm your macbook.